Which final battle world stands out the most in Kingdom Hearts?

I think End of The World. just cause of how surreal it is. plus it'd the only one we've never really revisited 

Scala ad Caelum because it was a beautifully designed world which was clearly once a thriving place but by KH3 was completely deserted, giving it an eery feel and making you wonder what happened there. Also the beautiful setting was an interesting contrast to the tense, dark mood as you prepared to fight Xehanort, though of course it turned into a very abstract and much darker setting when everything turned Doctor Strange. 

End of the World is severely underrated in this context IMHO. The idea of having a final battle in the remnants of fallen worlds is brilliant and this is definitely the world I would be looking forward to seeing have its full potential realized in a KH1 remake if ever it were to happen. The original version gave us the groundwork, but not the best possible execution. A Fragmentary Passage gave some excellent hints of how incredible this world could be in a fully realized form. 

The World That Never Was is the winner for me on a personal level in retrospect when factoring in all of its appearances and the stories we've had within it. Easily the world that feels the most special and appropriate for a final battle for reasons outside of spectacle and grandeur. It's the one thus far where they really nailed keeping us excited about the final act from the moment we get there until the credits rolled, every single time they gave it to us as the climactic world. 

Castle Oblivion is a compelling final world on paper, but like with End of the World the execution just wasn't there. I understand the limitations of course, but I still wish that when we finally got to the point in the game where the world card was Castle Oblivion itself that they'd done something, anything at all, to make it feel like an experience that was special compared to the rest from a gameplay standpoint. Another one that I would love to see the potential of fully realized through a remake if ever it were to happen, and IMHO this is saying something because Re:Chain of Memories was already such a great port/remake in many respects. 

The Keyblade Graveyard is one that I can thankfully say we did see the bulk of the potential of realized in KH3. The maze Xehanort set up had a lot more potential, but overall KH3 handled this world much better than Birth By Sleep. The ultimate letdown comes from the fact that the animation style for the Union Cross saga means we didn't get to see the nitty gritty parts of the Keyblade War in a more bloody, gore-filled, visceral, and indeed realistic way.

When you consider what the consoles and PCs at the time were capable of it is a bitter pill to swallow that they handled an event as important to the series lore as the Keyblade War in the way that they did (this is coming from someone who otherwise loves the art/animation style of the Union Cross Saga and Dark Road). 

Scala ad Caelum for me is a big letdown even with the Re:Mind DLC factored in. It's more spectacle and grandeur than it is substance. The fact that it's in essence a ghost town world is an interesting idea on paper, but they didn't do enough with the world gameplay or story wise IMHO for it to ever move the bar more than a few inches off the floor.

For a real world analogy it is like an archeologist getting to see the outside of a ruined city, but only being allowed to explore one percent of the insides of that ruined city for no other reason than every door and window within that ruined city being bolted shut or as old survival horror games would say "held fast by a powerful and unknown force", without a working solution to eventually enter said places.

Or gods forbid, even if the archeologist does get in, there's nothing to see because everything has been destroyed by the passage of time or collapsed to the point of being too dangerous to explore the most promising spaces of.  TLDR: Think of exploring an Egyptian tomb and finding absolutely nothing of note. That's what Scala ad Caelum was for me. If it returns in the future I hope they'll do more with it than they did for KH3/Re:Mind.

Edited July 17Jul 17 by FadedSparkle

I say Scala ad Caelum because it's exlusive to final battles. It's hard to think about final battles without thinking about Scala. That's why it stand out from the rest. Also additional points for background with bits of lore. 

In terms of gameplay, however, I must choose End of the World. It's gigantic and filled with surprising amount of content

End of the world but i’m voting the world that never was cause kh2 was my first kh game