Favorite Music: Well, I guess I'll have to say FF7. The battle themes (this includes bosses) were hard and sounded more like rock than any of the others. Aeris' theme almost made me cry, it was so emotional. And just overall, the tunes from FF7 were catchy and fun (in a good way). FF6 is a close runner-up.
Favorite Overall Characters: I'll have to go with FF6. That was my first FF, and it made a big impression on me in terms of best characters, best story, etc. And I like how the FF6 crew starts out kind of cartoony in ways, and throughout the game develop into real human-type characters you really identify with. This stands in stark contrast to FF9, where they just stayed cartoony.
Favorite Character: This is what I tell to everyone who asks this: Look at my user name. Good. Now you know. What I like about Cloud is that he is easily the most tragic, the most flawed FF character. And yet he manages to eventually conquer it all and defeat evil. That sounds a lot like an ancient Greek play, doesn't it? Well, no. Anyway, yeah, Cloud by a long shot.
Favorite Battle System: Ehhh... probably FF7. I loved using Materia, which was a welcome relief from the Junction system of FF8, which I had just beat with almost no sweat. FF6's Esper system was good, too.
Favorite Villain: This is who people usually say 50% of the time: Kefka! yes, Sephiroth was extremely bad-ass, but he just barely loses out to the transvestite clown thingie. Kefka's laugh was the BEST. And he was so cartoony at times... yeah, he's the best.
Favorite Ending: Once again, FF6. Sure, evey ending wraps stuff up, but the way in which FF6's ending was done just overwhelmed me. I think it's just your "I beat my first RPG game!" feeling that you can never really get again.
Favorite Storyline: Take a guess. Yep, it's FF6! Like I said, everything just... comes together, in a way I really can't explain. FF6 was a magical experience the entire way through, and I still haven't gotten over it. It was my first FF, and, in my opinion, the best. The characters were fun, the villain was a freaking evil clown with a memorable laugh, and the whole game was just magic. End. Of. Story.