I dunno about anyone else, but I had a hard time buying Keaton as Bruce Wayne/Batman, mostly because all he ever did was comedy stuff.
Tim Burton seems to pick an actor and use the shit out of him, Keaton was Beetlejuice, and if it had been any later we might have been stuck with Johnny Depp.
Christian Bale is okay, but Ledger stole the movie in The Dark Knight.
I liked Ledger, RIP, but I didn't as Batman.