I hated playing as Terra the most. He's so slow, he's the worst to use when fighting the secret bosses.

to be honest i don't hate any of them

but terra was my least  favourite character (but still i don't hate him)

They all had their positives and negatives... Terra was too slow I felt, but his strength and HP was a definite bonus. Ven was too fast sometimes, though the speed could also be an advantage. And I'm a fan of dodge roll, hahaa. Aqua was my favourite to play as because magic~ And carthweel and barrier are unmatched as great defenses. The biggest downside is that she's the physically weakest and i kept getting owned in the beginning when playing on any level higher than standard, haha. 

I really REALLY hate the ending of Aqua's story also Ven's. it makes me mad also sad.