I suppose it depends a bit on your taste in movies. Half of being a good actor is your film selection - look at Mel Gibson and Sylvester Stallone - average actors that made a living out of consistently choosing the right projects to get involved in. Bale definitely has a history of choosing roles requiring a little more testosterone. Let's face it, Leo is the artsy one. But also, that requires a lot more skill for an actor IMO, thus Leo is the easy choice here.
My votes on the categories I just made up:
Childhood films: DiCaprio (What's Eating Gilbert Grape)
Classical style films: DiCaprio (Gangs of New York)
Action flicks: Bale (Batman trilogy/Terminator: Salvation)
Mystery/Adventure: DiCaprio (Catch Me If You Can) I like "Prestige" but Scarlett may have something to do with that.
Psychological Thrillers: Push (American Psycho/Bale - Shutter Island/DiCaprio) I have yet to see "Inception" but my guess is that will sway my vote to Leo.
Blockbusters: DiCaprio (Titanic)
Neither is really done anything of note in the Comedy or Romantic Comedy categories to my knowledge. If they have, it wasn't noteworthy enough for my wife to convince me to watch.