Batman Begins by a long shot. Second would have to be Returns, but mostly because of Christopher Walken. Christopher Walken is just that cool that I can overlook a movie that completely craps on the Batman mythos. If i'd never heard of Batman, and knew nothing of his villains and their true backstories, i'd probably enjoy Batman Returns a whole hell of a lot.
Also, I place Batman and Robin over Batman Forever. Batman and Robin is bad to the point of actually being somewhat enjoyable, whereas Forever is just plain terrible. Besides, they ruined one of my favorite villains. A Two-Face that giggles like a maniac, and flips his coin repeatedly to get the desired outcome!?!? Unforgivable.