Daryl's theme just rawks so hard.

I like Shadow's, Setzer's, and Rachel's (If Rachel's theme is "Forever Rachel", at least) also. Kefka's is nice. And Terra's (If by Terra's we mean "Wanderer of Time"... I've heard it debated on if that was really her theme or not. If it is, then it's a toss up between Daryl's and Terra's).