SweetYetSalty

Balthier and Fran from FFXII. I think they would have an interesting dynamic with the main cast and I just love those two. I also wouldn't mind seeing Cecil or Kain from FFIV. Or Kefka from FFVI.
To be honest though, if we could get some characters from games other than FFVII, FFVIII and FFX and X-2, that alone would satisfy me. I'm sick of only seeing characters from those entries. But my top choices are the ones mentioned above.

For me my first choice would be Zidane from FF9 as I think his personality would make him a interesting character in the KH series and I think it would be cool if he was one of the residents in Twilight Town as him and Vivi are friends in FF9 so it would be a cool reference. Although if I could choose another character I would pick Red XIII and I think it would be cool if he was in Radiant Garden as almost every Final Fantasy character in that world is one of his friends in FF7. 
Who would everyone else pick?

Sora and Riku are often used as the origin for many staples of the series that then get used for other characters which leads to them no longer feeling unique for those things. For example Sora goes from "The Keyblade Master" to one of three prospective Keyblade Masters in the very first game thanks to Riku and Mickey. Sora (and Xehanort) also both feel less special the more they introduce new versions of them. By the time they introduced Ventus and Young Xehanort the whole idea of a new Sora or Xehanort felt stale and it was easy to just stop caring about their newest versions.

Kairi especially suffered from that thanks to Namine and Xion, but she never felt special to begin with creating the opposite problem (just because the devs insist on calling you special doesn't mean you are they need to do something with her that makes it clear she's special for her to feel special) in that Namine and Xion felt special and unique while Kairi still felt like someone "special because the devs say so" instead of because she had actually done something to construe her as actually special. Apologies to those who like Kairi I'm just telling it like it is.

Riku has his whole Warrior of the Dawn arc going on which would be a lot more special if Terra hadn't come along in Birth By Sleep (though it's partially alleviated in that they're different enough that they still feel special in other ways). The Recusant Sigil can also be traced back to first displayed on Riku before it was ever a thing within series lore. Also it could have been one off artistic design choice, but I always wondered about Riku having wings never really coming to fruition in KH1. Merging with a winged dream eater in DDD felt like they took an opportunity to resurrect a long dropped idea of winged Riku.

Then there's the matter of Xion evolving from a special replica to a nobody to a somebody which made her progressively less unique and special although in that case it's what most of the fans wanted for her. Same applies to Roxas having to merge back with Sora. As perfect an execution of a tragic tale as Roxas having to merge back with Sora was none of the fans wanted that to be his end, but Roxas becoming his own somebody instead of Sora being his somebody took what actually made Roxas a unique nobody away. All the others are their own somebodies rather than someone else's. To quote SuperButterBuns from her DDD for Beginners "Axel who is not Axel, but low-key is still very much Axel."

I was thinking about putting this in but forgot haha. She doesn't feel unique in this case anymore. Like, her, Roxas, Naminé, and half the Organization were/are using Replicas. 
 
For Ansem SOD that was his own 'heart's' desire but for Xemnas? I'm not sure anymore lol
I still just don't understand why Sora's not a Keyblade Master. He saved the worlds TWICE. He sealed all the sleeping Keyholes in the Mark of Mastery exam and Riku didn't even seal the real ones. And he was almost made into Xehanort's vessel because MASTER YEN SID DECIDED TO PUT THEM INTO THE SLEEPING REALM WHICH THEY AREN'T FAMILIAR WITH!! He also was aware that Master Xehanort was going to inevitably return; he should have known that Sora and Riku were going to be targeted. Like, C'MON YEN SID!! You're supposed to be a wise sorcerer so make some wise choices! Riku earned his Mark but Sora's a real deal too! I'll be forever angry with you Yen Sid, you who is always sitting on that stupid chair!!

I was going to make a list but Double OKP nearly listed everything I was going to say. Especially in regards to Roxas, Xion, Sora, and Apprentice Xehanort. Still I will stubbornly make one anyway lol.
1: Roxas~ Roxas use to be very unique among the Organization. No memories, amnesia, Keyblade wielder. This was unheard of among Nobodies. Roxas use to be a big deal in the Organization but now? Now we have like potentially six wielders in the Organization, made worse by the fact that Xemnas knew numbers 9-12 were connected to Keyblades. I don't know if Luxord or Demyx were wielders, but Roxas's importance in the group feels lost now. Marluxia also has memory issues, just like Roxas, and use to wield a Keyblade. If Xemnas experimented on him I'm sure they could find a way for him to summon his Keyblade back. Also Xemnas now has two Keyblade wielders he's connected to and should be able to dual wield. I'm bias since Roxas is my favorite character.
2: Xion~ Xion was originally made to replace Roxas due to their Keyblade connection. She was special because of her ties to Roxas and Sora. While she's still kinda unique, a lot of it has gone away. Now that characters can use Replica bodies for whoever needs a body, Xion's Replica story almost feels secondary to how KH3 used them. I always loved how weird Xion operated, being a Replica, her hood trick, everything. But all that feels like it's not there anymore due to the new Replica lore.
3: Sora~ I feel like Sora being a Keyblade wielder is no longer this unique thing. It's not that I don't like that there are other Keyblade wielders. I love me some Keyblades. But I feel they downgrade Sora to prop up the master title and it shows in the games following BBS. Sora didn't get passed down the power, he earned it. He is literally one of the few characters who truly earned a Keyblade. But they have been backpedaling that point. Now he feels like a random wild card rather then a hero to be respected.
4: Apprentice Xehanort~ Basically this guy isn't a character anymore. Ever since we got old man Xehanort and Terranort, this version has just become non-existent. Even with Melody of Memory when they try to give him a role, now he feels like a character completely separate from the Xehanort line period. His story with Ansem the Wise use to be something worth exploring. Now it feels like a waste of time, because I know who this guy really is is far above Ansem the Wise.
5: Ansem and Xemnas~ Once DDD revealed they were doing old man Xehanort's bidding to some degree, these two major villains of KH1 and KH2/Days felt like pawns and lackeys. Now whenever I look at their plans I wonder if it's there's or the old mans? 
6: Ansem the Wise~ Remember when this guy was Xemnas's arch enemy? Remember the story of him losing his name, kingdom, and everything to Apprentice Xehanort? This all feels unimportant now to the stuff that has been going on. Yensid replaced him as a reliable source of knowledge for Mickey. A relic of the past
7:  Riku~ I'm putting him here because now we have a lot of characters that use to be bad but are now good whether they were under possession or not. Isa, Axel, Terra, almost every Organization member. Just remember Riku was the original bad boy turned good.
8: Mickey~ Shocking choice huh? Mickey use to be a voice of wisdom and a leader. But like Ansem the Wise, Yensid has replaced him as the wisest character in the series. Mickey also use to be really powerful back in the day. Now he feels like everyone else, not special at all.
 

I was going to make a list but Double OKP nearly listed everything I was going to say. Especially in regards to Roxas, Xion, Sora, and Apprentice Xehanort. Still I will stubbornly make one anyway lol.
1: Roxas~ Roxas use to be very unique among the Organization. No memories, amnesia, Keyblade wielder. This was unheard of among Nobodies. Roxas use to be a big deal in the Organization but now? Now we have like potentially six wielders in the Organization, made worse by the fact that Xemnas knew numbers 9-12 were connected to Keyblades. I don't know if Luxord or Demyx were wielders, but Roxas's importance in the group feels lost now. Marluxia also has memory issues, just like Roxas, and use to wield a Keyblade. If Xemnas experimented on him I'm sure they could find a way for him to summon his Keyblade back. Also Xemnas now has two Keyblade wielders he's connected to and should be able to dual wield. I'm bias since Roxas is my favorite character.
2: Xion~ Xion was originally made to replace Roxas due to their Keyblade connection. She was special because of her ties to Roxas and Sora. While she's still kinda unique, a lot of it has gone away. Now that characters can use Replica bodies for whoever needs a body, Xion's Replica story almost feels secondary to how KH3 used them. I always loved how weird Xion operated, being a Replica, her hood trick, everything. But all that feels like it's not there anymore due to the new Replica lore.
3: Sora~ I feel like Sora being a Keyblade wielder is no longer this unique thing. It's not that I don't like that there are other Keyblade wielders. I love me some Keyblades. But I feel they downgrade Sora to prop up the master title and it shows in the games following BBS. Sora didn't get passed down the power, he earned it. He is literally one of the few characters who truly earned a Keyblade. But they have been backpedaling that point. Now he feels like a random wild card rather then a hero to be respected.
4: Apprentice Xehanort~ Basically this guy isn't a character anymore. Ever since we got old man Xehanort and Terranort, this version has just become non-existent. Even with Melody of Memory when they try to give him a role, now he feels like a character completely separate from the Xehanort line period. His story with Ansem the Wise use to be something worth exploring. Now it feels like a waste of time, because I know who this guy really is is far above Ansem the Wise.
5: Ansem and Xemnas~ Once DDD revealed they were doing old man Xehanort's bidding to some degree, these two major villains of KH1 and KH2/Days felt like pawns and lackeys. Now whenever I look at their plans I wonder if it's there's or the old mans? 
6: Ansem the Wise~ Remember when this guy was Xemnas's arch enemy? Remember the story of him losing his name, kingdom, and everything to Apprentice Xehanort? This all feels unimportant now to the stuff that has been going on. Yensid replaced him as a reliable source of knowledge for Mickey. A relic of the past
7:  Riku~ I'm putting him here because now we have a lot of characters that use to be bad but are now good whether they were under possession or not. Isa, Axel, Terra, almost every Organization member. Just remember Riku was the original bad boy turned good.
8: Mickey~ Shocking choice huh? Mickey use to be a voice of wisdom and a leader. But like Ansem the Wise, Yensid has replaced him as the wisest character in the series. Mickey also use to be really powerful back in the day. Now he feels like everyone else, not special at all.
 

I was going to make a list but Double OKP nearly listed everything I was going to say. Especially in regards to Roxas, Xion, Sora, and Apprentice Xehanort. Still I will stubbornly make one anyway lol.
1: Roxas~ Roxas use to be very unique among the Organization. No memories, amnesia, Keyblade wielder. This was unheard of among Nobodies. Roxas use to be a big deal in the Organization but now? Now we have like potentially six wielders in the Organization, made worse by the fact that Xemnas knew numbers 9-12 were connected to Keyblades. I don't know if Luxord or Demyx were wielders, but Roxas's importance in the group feels lost now. Marluxia also has memory issues, just like Roxas, and use to wield a Keyblade. If Xemnas experimented on him I'm sure they could find a way for him to summon his Keyblade back. Also Xemnas now has two Keyblade wielders he's connected to and should be able to dual wield. I'm bias since Roxas is my favorite character.
2: Xion~ Xion was originally made to replace Roxas due to their Keyblade connection. She was special because of her ties to Roxas and Sora. While she's still kinda unique, a lot of it has gone away. Now that characters can use Replica bodies for whoever needs a body, Xion's Replica story almost feels secondary to how KH3 used them. I always loved how weird Xion operated, being a Replica, her hood trick, everything. But all that feels like it's not there anymore due to the new Replica lore.
3: Sora~ I feel like Sora being a Keyblade wielder is no longer this unique thing. It's not that I don't like that there are other Keyblade wielders. I love me some Keyblades. But I feel they downgrade Sora to prop up the master title and it shows in the games following BBS. Sora didn't get passed down the power, he earned it. He is literally one of the few characters who truly earned a Keyblade. But they have been backpedaling that point. Now he feels like a random wild card rather then a hero to be respected.
4: Apprentice Xehanort~ Basically this guy isn't a character anymore. Ever since we got old man Xehanort and Terranort, this version has just become non-existent. Even with Melody of Memory when they try to give him a role, now he feels like a character completely separate from the Xehanort line period. His story with Ansem the Wise use to be something worth exploring. Now it feels like a waste of time, because I know who this guy really is is far above Ansem the Wise.
5: Ansem and Xemnas~ Once DDD revealed they were doing old man Xehanort's bidding to some degree, these two major villains of KH1 and KH2/Days felt like pawns and lackeys. Now whenever I look at their plans I wonder if it's there's or the old mans? 
6: Ansem the Wise~ Remember when this guy was Xemnas's arch enemy? Remember the story of him losing his name, kingdom, and everything to Apprentice Xehanort? This all feels unimportant now to the stuff that has been going on. Yensid replaced him as a reliable source of knowledge for Mickey. A relic of the past
7:  Riku~ I'm putting him here because now we have a lot of characters that use to be bad but are now good whether they were under possession or not. Isa, Axel, Terra, almost every Organization member. Just remember Riku was the original bad boy turned good.
8: Mickey~ Shocking choice huh? Mickey use to be a voice of wisdom and a leader. But like Ansem the Wise, Yensid has replaced him as the wisest character in the series. Mickey also use to be really powerful back in the day. Now he feels like everyone else, not special at all.
 

1. Sora
In KH1 and Re:COM, Sora was referred to as the Keyblade master. He was special and unique because he wielded a Keyblade. He also commonly posed hands-behind-head. But now there are so many other Keyblade wielders and it turns out that Sora didn't earn the title of 'Keyblade Master'(I still don't get why he didn't. He sealed all the keyholes! Yen Sid!! *glares at wizard sitting on chair*) Yes, he's still special but he isn't as unique as he was before. And turns out that Ventus was the first person to pose hands-behind-head and then Eraqus after him!
2. Roxas 
Well, he was unique because he was the Organization's Keyblade wielder! He(& Xion) didn't have any memories before the Organization, which was the main part of his uniqueness. He was also one of the only Nobodies who didn't look like their original self. But then! Marluxia and Larxene's backstory came along and it turns out that Roxas wasn't the only one who was amnesiac. And he wasn't the only Organization member to have a connection to the Keyblade. Also, he looks exactly like Ventus! 
3. Xion
She is still unique but like Roxas, her amnesia isn't a unique feature anymore.
4. Apprentice Xehanort
A young man first introduced in KHII as an apprentice to Ansem the Wise. His Heartless was Ansem Seeker of Darkness and his Nobody was Xemnas. Xehanort was his name. But then came along Birth By Sleep where TWO 'Xehanorts' were introduced, Master Xehanort(an 80-ish-something-year old hunching man who has impressive combat skills for his age, and not to mention that in KHIII he is in his 90's?! which is even more decieving considering his physical power) and Terra-Xehanort, who turned out to be Apprentice Xehanort. Then in Dream Drop Distance, Young Xehanort(Master Xehanort's literal younger self) was introduced. Then it was revealed that Master Xehanort had formed an Organization...and each member vesseled a part of his heart, creating 13 Xehanorts! Now, who was the first Xehanort again?
(Can't think of anyone else, am I missing someone?)

1: Kingdom Hearts~ For gameplay and story this would equal my number one favorite game overall. It's simple, easy to follow, really fun to play and explore. I love everything about KH1. The original story, the Disney Worlds and how they were used, Sora's friendship with Donald and Goofy. The Riku rivalry, even Kairi for her limited screentime was a cute character. The FF characters were used well and this is the one title I always return to for a relaxing good time. It's got it all.
2: 358/2 Days~ For gameplay it's near the bottom, but story wise it's my second favorite in the series. I've never be emotionally engaged in a video game story before Days came along. This game turned a character I was lukewarm on (Roxas) into my all time favorite character. It made me love Organization XIII when I previously soured on them. It gave me Xion and my favorite trio of the series, the Sea-Salt Trio, and that alone makes me return to play the DS game, even though it's not the best to play. As said it's repetitive and some missions go from boring to tedious. But it's all worth it for the amazing characters the game gave me.
3: Kingdom Hearts 3~ Gameplay wise this is my second favorite KH game. Storywise, I'd rank KH1, Days, and maybe CoM above this one. What really put this one so high on the list is ReMind and Limitcut. Those contents alone were amazing and I love Data Greeting and fighting the Data Organization. The Disney Worlds were a improvement over KH2's but still didn't match KH1. Best Gummi Ship gameplay in the series, and the Keyblade Graveyard reunions are some of my favorite moments in the series. The added DLC content just made it all even better.
4: Melody of Memories~Story wise probably one of the worst if not the worst. The reason it ranks so high is the gameplay. This is the most addictive gameplay I have ever done, and I previously was not into rhythm games. I love the music, the tracks, the visual worlds we run through. Playing as my favorite trio in any world I want, you better believe I used RAX forever. Collect the cards of my favorite characters and enemies. Full chain and All Excellent songs and improve my score. I love this game, it didn't even need a story. That's why it ranks so high on my list because of the gameplay. This is also the first (and only) game I platinum'd. If not for gameplay this would be at the very bottom of my list.
5: Chain of Memories~The reverse Melody of Memories. I cannot stand the card battle system at all. This is bottom tier in terms of gameplay for me. But I adore the story. I prefer Riku's story over Sora's, but the latters isn't too bad. I think this batch of Organization members were more memorable in this game then most of the ones introduced in KH2, honestly. At least Larxene, Vexen, and Marluxia. The game setup a lot of stuff lore wise for the series, and even though I'm neutral on her today, Namine was absolutely lovable in this game.
6: Kingdom Hearts 2~ I am one of the biggest nitpickers of this game. Gameplay wise I will agree this is a near masterpiece of a game, with good controls, solid bosses, and cool enemy designs. I say near because things like the Light Cycle and flying carpet segments exist. Story wise This game is good but not nearly as great as everyone makes it out to be. This game has aged the worse due to all the retcons the series has undergone and now certain things in this game no longer hit as hard as they were intended. Organization XIII was pretty generic here too, I appreciate them today, but back then I remember not being terribly impressed with any of them minus Xemnas, Axel, and Demyx. The Disney Worlds are hit or miss. Some are the best in the overall series and others are the worst. The Sora, Riku, Kairi reunion however still remains one of my fave moments in the series. Also the KH2 Manga is way cooler then the game.
7: Birth By Sleep~ Looking back at the history of this game, this is where most of the big retcons started. Some are good, some are bad, some are really confusing. Gameplay wise this as a okay title. Better then Days and CoM but not on the level of the main numbered titles, in fact this game made me appreciate those titles more. Storywise this is where things get interesting. I think the story of BBS is very good. The characters, however needed some work. I didn't really get invested in the Wayfinder Trio as a trio until 0.2, KH3, and the BBS novel. They aren't bad characters, but I never bought into them being the close friends the game kept telling me they were. They are much better now, but this was a rocky start. But I did like them as individuals.
8: Dream Drop Distance~From here on out I cannot judge by gameplay because these are the games I never played only watched the cutscenes or read their novels. DDD I have never played, but the story I watched and later read. It's not as bad as many make it out to be. I don't mind time travel, but this game made it so complicated that it's almost hard to enjoy. They also tried to tie everything together when it didn't need to be and that's why so many inconsistent messiness comes from this game. KH3 unfortunately continues some of the trends found in this game. That said it has good stuff in it too storywise. It gave me Sora meeting Roxas and actually talking to him. KH2 didn't even do that.
9: ReCoded~ This one is good for the characters of Data Sora, Riku, Roxas, and Namine. I think all of them were charming data clones of the real thing. In my opinion Data Sora and Data Roxas had better first interactions then the real ones in KH2. Yes I am shading KH2 a lot now. Otherwise nothing really happens here.
10: The rest~ I view all the Union X/Chi/Back Cover stuff the same. Interesting stories that caught my attention but minus like a select few, their characters all need work. I can't tell you anything about the Dandelions because they don't feel like real characters, that I'm attached too. Master of Masters and Ava are the only ones I truly like. I don't really count 0.2 as it's own thing.
Separated the list looks like this.
Story
1: Kingdom Hearts 
2: 358/2 Days
3: Kingdom Hearts III
4: Chain of Memories
5: Birth By Sleep/0.2/ Kingdom Hearts II
6:Dream Drop Distance/ReCoded
7:Union X/Back Cover
8:Melody of Memories
Gameplay
1: Kingdom Hearts 
2: Kingdom Hearts III
3: Melody of Memories
4: Kingdom Hearts II
5: Birth By Sleep
6: 358/2 Days
7: Chain if Memories
Edit: I just can never decide if I like BBS or KHII more as a story so they are tied. Same with DDD and Coded.

1: Kingdom Hearts~ For gameplay and story this would equal my number one favorite game overall. It's simple, easy to follow, really fun to play and explore. I love everything about KH1. The original story, the Disney Worlds and how they were used, Sora's friendship with Donald and Goofy. The Riku rivalry, even Kairi for her limited screentime was a cute character. The FF characters were used well and this is the one title I always return to for a relaxing good time. It's got it all.
2: 358/2 Days~ For gameplay it's near the bottom, but story wise it's my second favorite in the series. I've never be emotionally engaged in a video game story before Days came along. This game turned a character I was lukewarm on (Roxas) into my all time favorite character. It made me love Organization XIII when I previously soured on them. It gave me Xion and my favorite trio of the series, the Sea-Salt Trio, and that alone makes me return to play the DS game, even though it's not the best to play. As said it's repetitive and some missions go from boring to tedious. But it's all worth it for the amazing characters the game gave me.
3: Kingdom Hearts 3~ Gameplay wise this is my second favorite KH game. Storywise, I'd rank KH1, Days, and maybe CoM above this one. What really put this one so high on the list is ReMind and Limitcut. Those contents alone were amazing and I love Data Greeting and fighting the Data Organization. The Disney Worlds were a improvement over KH2's but still didn't match KH1. Best Gummi Ship gameplay in the series, and the Keyblade Graveyard reunions are some of my favorite moments in the series. The added DLC content just made it all even better.
4: Melody of Memories~Story wise probably one of the worst if not the worst. The reason it ranks so high is the gameplay. This is the most addictive gameplay I have ever done, and I previously was not into rhythm games. I love the music, the tracks, the visual worlds we run through. Playing as my favorite trio in any world I want, you better believe I used RAX forever. Collect the cards of my favorite characters and enemies. Full chain and All Excellent songs and improve my score. I love this game, it didn't even need a story. That's why it ranks so high on my list because of the gameplay. This is also the first (and only) game I platinum'd. If not for gameplay this would be at the very bottom of my list.
5: Chain of Memories~The reverse Melody of Memories. I cannot stand the card battle system at all. This is bottom tier in terms of gameplay for me. But I adore the story. I prefer Riku's story over Sora's, but the latters isn't too bad. I think this batch of Organization members were more memorable in this game then most of the ones introduced in KH2, honestly. At least Larxene, Vexen, and Marluxia. The game setup a lot of stuff lore wise for the series, and even though I'm neutral on her today, Namine was absolutely lovable in this game.
6: Kingdom Hearts 2~ I am one of the biggest nitpickers of this game. Gameplay wise I will agree this is a near masterpiece of a game, with good controls, solid bosses, and cool enemy designs. I say near because things like the Light Cycle and flying carpet segments exist. Story wise This game is good but not nearly as great as everyone makes it out to be. This game has aged the worse due to all the retcons the series has undergone and now certain things in this game no longer hit as hard as they were intended. Organization XIII was pretty generic here too, I appreciate them today, but back then I remember not being terribly impressed with any of them minus Xemnas, Axel, and Demyx. The Disney Worlds are hit or miss. Some are the best in the overall series and others are the worst. The Sora, Riku, Kairi reunion however still remains one of my fave moments in the series. Also the KH2 Manga is way cooler then the game.
7: Birth By Sleep~ Looking back at the history of this game, this is where most of the big retcons started. Some are good, some are bad, some are really confusing. Gameplay wise this as a okay title. Better then Days and CoM but not on the level of the main numbered titles, in fact this game made me appreciate those titles more. Storywise this is where things get interesting. I think the story of BBS is very good. The characters, however needed some work. I didn't really get invested in the Wayfinder Trio as a trio until 0.2, KH3, and the BBS novel. They aren't bad characters, but I never bought into them being the close friends the game kept telling me they were. They are much better now, but this was a rocky start. But I did like them as individuals.
8: Dream Drop Distance~From here on out I cannot judge by gameplay because these are the games I never played only watched the cutscenes or read their novels. DDD I have never played, but the story I watched and later read. It's not as bad as many make it out to be. I don't mind time travel, but this game made it so complicated that it's almost hard to enjoy. They also tried to tie everything together when it didn't need to be and that's why so many inconsistent messiness comes from this game. KH3 unfortunately continues some of the trends found in this game. That said it has good stuff in it too storywise. It gave me Sora meeting Roxas and actually talking to him. KH2 didn't even do that.
9: ReCoded~ This one is good for the characters of Data Sora, Riku, Roxas, and Namine. I think all of them were charming data clones of the real thing. In my opinion Data Sora and Data Roxas had better first interactions then the real ones in KH2. Yes I am shading KH2 a lot now. Otherwise nothing really happens here.
10: The rest~ I view all the Union X/Chi/Back Cover stuff the same. Interesting stories that caught my attention but minus like a select few, their characters all need work. I can't tell you anything about the Dandelions because they don't feel like real characters, that I'm attached too. Master of Masters and Ava are the only ones I truly like. I don't really count 0.2 as it's own thing.
Separated the list looks like this.
Story
1: Kingdom Hearts 
2: 358/2 Days
3: Kingdom Hearts III
4: Chain of Memories
5: Birth By Sleep/0.2/ Kingdom Hearts II
6:Dream Drop Distance/ReCoded
7:Union X/Back Cover
8:Melody of Memories
Gameplay
1: Kingdom Hearts 
2: Kingdom Hearts III
3: Melody of Memories
4: Kingdom Hearts II
5: Birth By Sleep
6: 358/2 Days
7: Chain if Memories
Edit: I just can never decide if I like BBS or KHII more as a story so they are tied. Same with DDD and Coded.

1: Kingdom Hearts~ For gameplay and story this would equal my number one favorite game overall. It's simple, easy to follow, really fun to play and explore. I love everything about KH1. The original story, the Disney Worlds and how they were used, Sora's friendship with Donald and Goofy. The Riku rivalry, even Kairi for her limited screentime was a cute character. The FF characters were used well and this is the one title I always return to for a relaxing good time. It's got it all.
2: 358/2 Days~ For gameplay it's near the bottom, but story wise it's my second favorite in the series. I've never be emotionally engaged in a video game story before Days came along. This game turned a character I was lukewarm on (Roxas) into my all time favorite character. It made me love Organization XIII when I previously soured on them. It gave me Xion and my favorite trio of the series, the Sea-Salt Trio, and that alone makes me return to play the DS game, even though it's not the best to play. As said it's repetitive and some missions go from boring to tedious. But it's all worth it for the amazing characters the game gave me.
3: Kingdom Hearts 3~ Gameplay wise this is my second favorite KH game. Storywise, I'd rank KH1, Days, and maybe CoM above this one. What really put this one so high on the list is ReMind and Limitcut. Those contents alone were amazing and I love Data Greeting and fighting the Data Organization. The Disney Worlds were a improvement over KH2's but still didn't match KH1. Best Gummi Ship gameplay in the series, and the Keyblade Graveyard reunions are some of my favorite moments in the series. The added DLC content just made it all even better.
4: Melody of Memories~Story wise probably one of the worst if not the worst. The reason it ranks so high is the gameplay. This is the most addictive gameplay I have ever done, and I previously was not into rhythm games. I love the music, the tracks, the visual worlds we run through. Playing as my favorite trio in any world I want, you better believe I used RAX forever. Collect the cards of my favorite characters and enemies. Full chain and All Excellent songs and improve my score. I love this game, it didn't even need a story. That's why it ranks so high on my list because of the gameplay. This is also the first (and only) game I platinum'd. If not for gameplay this would be at the very bottom of my list.
5: Chain of Memories~The reverse Melody of Memories. I cannot stand the card battle system at all. This is bottom tier in terms of gameplay for me. But I adore the story. I prefer Riku's story over Sora's, but the latters isn't too bad. I think this batch of Organization members were more memorable in this game then most of the ones introduced in KH2, honestly. At least Larxene, Vexen, and Marluxia. The game setup a lot of stuff lore wise for the series, and even though I'm neutral on her today, Namine was absolutely lovable in this game.
6: Kingdom Hearts 2~ I am one of the biggest nitpickers of this game. Gameplay wise I will agree this is a near masterpiece of a game, with good controls, solid bosses, and cool enemy designs. I say near because things like the Light Cycle and flying carpet segments exist. Story wise This game is good but not nearly as great as everyone makes it out to be. This game has aged the worse due to all the retcons the series has undergone and now certain things in this game no longer hit as hard as they were intended. Organization XIII was pretty generic here too, I appreciate them today, but back then I remember not being terribly impressed with any of them minus Xemnas, Axel, and Demyx. The Disney Worlds are hit or miss. Some are the best in the overall series and others are the worst. The Sora, Riku, Kairi reunion however still remains one of my fave moments in the series. Also the KH2 Manga is way cooler then the game.
7: Birth By Sleep~ Looking back at the history of this game, this is where most of the big retcons started. Some are good, some are bad, some are really confusing. Gameplay wise this as a okay title. Better then Days and CoM but not on the level of the main numbered titles, in fact this game made me appreciate those titles more. Storywise this is where things get interesting. I think the story of BBS is very good. The characters, however needed some work. I didn't really get invested in the Wayfinder Trio as a trio until 0.2, KH3, and the BBS novel. They aren't bad characters, but I never bought into them being the close friends the game kept telling me they were. They are much better now, but this was a rocky start. But I did like them as individuals.
8: Dream Drop Distance~From here on out I cannot judge by gameplay because these are the games I never played only watched the cutscenes or read their novels. DDD I have never played, but the story I watched and later read. It's not as bad as many make it out to be. I don't mind time travel, but this game made it so complicated that it's almost hard to enjoy. They also tried to tie everything together when it didn't need to be and that's why so many inconsistent messiness comes from this game. KH3 unfortunately continues some of the trends found in this game. That said it has good stuff in it too storywise. It gave me Sora meeting Roxas and actually talking to him. KH2 didn't even do that.
9: ReCoded~ This one is good for the characters of Data Sora, Riku, Roxas, and Namine. I think all of them were charming data clones of the real thing. In my opinion Data Sora and Data Roxas had better first interactions then the real ones in KH2. Yes I am shading KH2 a lot now. Otherwise nothing really happens here.
10: The rest~ I view all the Union X/Chi/Back Cover stuff the same. Interesting stories that caught my attention but minus like a select few, their characters all need work. I can't tell you anything about the Dandelions because they don't feel like real characters, that I'm attached too. Master of Masters and Ava are the only ones I truly like. I don't really count 0.2 as it's own thing.
Separated the list looks like this.
Story
1: Kingdom Hearts 
2: 358/2 Days
3: Kingdom Hearts III
4: Chain of Memories
5: Birth By Sleep/0.2/ Kingdom Hearts II
6:Dream Drop Distance/ReCoded
7:Union X/Back Cover
8:Melody of Memories
Gameplay
1: Kingdom Hearts 
2: Kingdom Hearts III
3: Melody of Memories
4: Kingdom Hearts II
5: Birth By Sleep
6: 358/2 Days
7: Chain if Memories
Edit: I just can never decide if I like BBS or KHII more as a story so they are tied. Same with DDD and Coded.

The whole game leading up to the Keyblade Graveyard was the longest side content it took me to complete.

The Deep End
Night on Bald Mountain
100 Acre Woods and the mini game theme
Graceful Assassin
The Corrupted
Nearly every track in KH3, ranging from Toy Box Jam, to Monstropolis's regular and fire themes, to Olympus and the titans, to Hearts as One, Replicas, Face My Fears and more.
The entire Data Organization remixes and Yozora's theme.
 

I’m curious if you could pick any songs to add into Melody of Memory what songs would you choose? as much as I would like to add every song that wasn’t in the game, I’m only going to pick a few which would be:
Face My Fears
Sora’s Sacrifice ( I know it could be counted as another version of Simple and Clean but it still considered it’s own song)
Hearts as One ( Again I know it’s just the Other Promise and Vector To The Heavens combined and both are already in the game but once again it still counts)
What songs would everyone else pick?
 

I don't want to count Keyblades, as I feel it's cheating. So I'll make a list without the Keyblades.
1: Lunatic (Saix)
2: Arpeggio (Demyx)
3: Lindworm (Xaldin)
4: Graceful Dahlia (Marluxia)
5: Ethereal Blades (Xemnas)
6: Eternal Flames (Axel)
7: Sharpshooter (Xigbar)
8: Book of Retribution (Zexion)
9: Fair Game (Luxord)
10: Skysplitter (Lexaeus)
11: Foudre (Larxene)
12: Frozen Pride (Vexen)

The best part of this game is the Sea Salt Trio hanging out on the main menu screen and I'll hear no debate on this

A lot of the Organization XIII members weapons have really cool and interesting designs in my opinion and if I had to choose one my personal favourite would have to be Marluxia’s Graceful Dahlia as I just really like the colour scheme and design of his weapon overall and it looks really cool in battle, also I think the way he summons it before his boss fight in Re :Chain of Memories looked awesome and another reason why it’s probably my favourite Organization XIII weapon is simply because Scythes are probably my favourite video game weapon.

i quite like demyx's sitars, mayabe i just like it when people fight with instruments 

Axel's pizza joke weapons, Saix's banana  
Joke weapons aside I almost want to choose Roxas's Oathkeeper and Oblivion keyblades, but I feel like that's cheating.  For me it might actually be Axel's Eternal Flames Chakrams. Nothing too crazy going on with them design wise, but I guess I like how sleek and menacing they look, you know whenever he pulls them out it's about to go down.  

2020 was a very strange year, but we made it! It's 2021!
HAPPY NEW YEAR EVERYONE!! God bless!

This is quite the interesting question. For me I prefer the characters I can relate to on a personal level. Ones that I enjoy seeing interact with one another, and who's stories unfold as we go on a journey with them. Being entertaining also helps too. Doesn't matter if it is a hero or villain. Both have those characters on their sides. Basically the characters I know inside and out and are well fleshed out are the ones I prefer.
But to dig further into it, the original Organization XIII is one of my favorite elements of Kingdom Hearts, because of all the dynamics that go into. The politics they employ, the hierarchy, the backstabbing, the coworker relationships, the planning, the history, and why they are needed in the group. Almost everything I love about Organization XIII. That being said not all the Organization members fit the category I stated above, or only fit one. Most of the Organization members started out as stereotypes and archetypes. The ones the deviate from those and have more then one character trait are the standouts of the group, and get extra story. However some of the more static members are the ones that really don't get story and are just there with their one personality trait. They are still very entertaining but not fleshed out.
With the heroes it's a little easier for the ones you play as, since its easy to get attached to them since you go through their story with them. That being said not all the heroes are as fleshed out as they can be. There is even a few characters we still don't really know much about, despite them being on the covers of big KH titles.
 

This is quite the interesting question. For me I prefer the characters I can relate to on a personal level. Ones that I enjoy seeing interact with one another, and who's stories unfold as we go on a journey with them. Being entertaining also helps too. Doesn't matter if it is a hero or villain. Both have those characters on their sides. Basically the characters I know inside and out and are well fleshed out are the ones I prefer.
But to dig further into it, the original Organization XIII is one of my favorite elements of Kingdom Hearts, because of all the dynamics that go into. The politics they employ, the hierarchy, the backstabbing, the coworker relationships, the planning, the history, and why they are needed in the group. Almost everything I love about Organization XIII. That being said not all the Organization members fit the category I stated above, or only fit one. Most of the Organization members started out as stereotypes and archetypes. The ones the deviate from those and have more then one character trait are the standouts of the group, and get extra story. However some of the more static members are the ones that really don't get story and are just there with their one personality trait. They are still very entertaining but not fleshed out.
With the heroes it's a little easier for the ones you play as, since its easy to get attached to them since you go through their story with them. That being said not all the heroes are as fleshed out as they can be. There is even a few characters we still don't really know much about, despite them being on the covers of big KH titles.
 

This is quite the interesting question. For me I prefer the characters I can relate to on a personal level. Ones that I enjoy seeing interact with one another, and who's stories unfold as we go on a journey with them. Being entertaining also helps too. Doesn't matter if it is a hero or villain. Both have those characters on their sides. Basically the characters I know inside and out and are well fleshed out are the ones I prefer.
But to dig further into it, the original Organization XIII is one of my favorite elements of Kingdom Hearts, because of all the dynamics that go into. The politics they employ, the hierarchy, the backstabbing, the coworker relationships, the planning, the history, and why they are needed in the group. Almost everything I love about Organization XIII. That being said not all the Organization members fit the category I stated above, or only fit one. Most of the Organization members started out as stereotypes and archetypes. The ones the deviate from those and have more then one character trait are the standouts of the group, and get extra story. However some of the more static members are the ones that really don't get story and are just there with their one personality trait. They are still very entertaining but not fleshed out.
With the heroes it's a little easier for the ones you play as, since its easy to get attached to them since you go through their story with them. That being said not all the heroes are as fleshed out as they can be. There is even a few characters we still don't really know much about, despite them being on the covers of big KH titles.
 

This is quite the interesting question. For me I prefer the characters I can relate to on a personal level. Ones that I enjoy seeing interact with one another, and who's stories unfold as we go on a journey with them. Being entertaining also helps too. Doesn't matter if it is a hero or villain. Both have those characters on their sides. Basically the characters I know inside and out and are well fleshed out are the ones I prefer.
But to dig further into it, the original Organization XIII is one of my favorite elements of Kingdom Hearts, because of all the dynamics that go into. The politics they employ, the hierarchy, the backstabbing, the coworker relationships, the planning, the history, and why they are needed in the group. Almost everything I love about Organization XIII. That being said not all the Organization members fit the category I stated above, or only fit one. Most of the Organization members started out as stereotypes and archetypes. The ones the deviate from those and have more then one character trait are the standouts of the group, and get extra story. However some of the more static members are the ones that really don't get story and are just there with their one personality trait. They are still very entertaining but not fleshed out.
With the heroes it's a little easier for the ones you play as, since its easy to get attached to them since you go through their story with them. That being said not all the heroes are as fleshed out as they can be. There is even a few characters we still don't really know much about, despite them being on the covers of big KH titles.
 

This is quite the interesting question. For me I prefer the characters I can relate to on a personal level. Ones that I enjoy seeing interact with one another, and who's stories unfold as we go on a journey with them. Being entertaining also helps too. Doesn't matter if it is a hero or villain. Both have those characters on their sides. Basically the characters I know inside and out and are well fleshed out are the ones I prefer.
But to dig further into it, the original Organization XIII is one of my favorite elements of Kingdom Hearts, because of all the dynamics that go into. The politics they employ, the hierarchy, the backstabbing, the coworker relationships, the planning, the history, and why they are needed in the group. Almost everything I love about Organization XIII. That being said not all the Organization members fit the category I stated above, or only fit one. Most of the Organization members started out as stereotypes and archetypes. The ones the deviate from those and have more then one character trait are the standouts of the group, and get extra story. However some of the more static members are the ones that really don't get story and are just there with their one personality trait. They are still very entertaining but not fleshed out.
With the heroes it's a little easier for the ones you play as, since its easy to get attached to them since you go through their story with them. That being said not all the heroes are as fleshed out as they can be. There is even a few characters we still don't really know much about, despite them being on the covers of big KH titles.