I guess my preference leans towards VI and VIII, but really I do like them all and for different reasons. III is a lot of fun but I don't play my DS very much so it isn't going anywhere e.e

Uhh...I liked X but was sort of insulted by how EASY it was, but the characters and story was really great and IX and X win for their NOT droopy mopey main characters. It's so nice to not follow around an anti-hero all the time.