I still don't get the hate you guys have for KHII. I really liked it.
Anyways, my reasoning for my list is:
KHI: Easily the best in the whole series. Great story, great gameplay, right amount of difficulty, and just overall a classic.
KHII: Great second chapter to the original. Love the addition of more fast paced action and brand new worlds! Although, I personally don't feel it shared the same sort of atmosphere as the first, and the ending wasn't as good (though still a great ending).
KHDDD: I really loved the gameplay of this one, the story was also neat! I actually didn't mind the time traveling addition, as we had already seen that done before. What ticks me off is their younger selves thing. Not that they're younger, just that they don't look like their KHI selves (especially Riku)
KHBBS Great story, great battle mechanics, but it ticked me off that I was going to the same worlds every time. That really bothered me. The character were great, though. But Aqua's and Terra's voice acting sucked >.<
KHDAYS: I love the story and the characters, but the repetive missions and limited worlds kinda bothered me. I hated missions like defeating the emerald serenade, but some missions were really fun! I liked the gameplay, though. Mission mode sucks though, since I don't have any else who plays KHDAYS D: I unlocked Mickey and Sora for nothing!
KHCOM: I won't lie, I actually dug the card gameplay, but the worlds sucked. I always skipped their cutscenes (except Destiny Islands and Twilight Town) The bosses were fun, though. I also LOVED the Castle Oblivion scenes.
KHCODED: Horrid story but I liked the gameplay. The Castle oblivion bit at the end was fun, too (Roxas!!!
)