Guess I'm the first to second it: IX
I liked the story, was able to work around the skill system (for all people's complaining about it, it's not that bad), loved the characters, and had fun with it. Sure people might complain that it's cartoony and ask how you can take it seriously, though these same people most likely never played up until Lindblum was attacked (walking around in the aftermath and seeing the damage is one of the few times where a huge number of deaths isn't just a statistic). Plus, the soundtrack was absolutely amazing.
Other than that, I really liked X (which had one of the best villains in gaming).
My most hated however are XII, VIII, and II.