I've been playing Kingdom Hearts since 2002 and the first game is still my favourite one. I really preferred when the game was about adventures and rescuing princesses from a witch. Also having a keyblade was actually unique back then. It was also nice how you didn't have to beat some post game super boss to get the Ultima Weapon.
My favourite character is probably Maleficent, she's not a keyblade master, a heartless or a nobody etc... Yet she's still one of the most feared characters in the game simply because she's strong and not because of some plot related nonsense. If you don't believe me go play Riku's story in Chain Of Memories, 3 of the Organization members are pissing themselves when they thought Maleficent was revived for a brief second. These same members are mentally prepared to anger some keyblade users and fight Xenmas along with the rest of the Organization.