I voted for Michael Keaton because he really did play a great Batman. He was completely unbelievable as Bruce Wayne, but his Batman was great.
Val Kilmer played a good Bruce Wayne, but his Batman was just godawful.
George Clooney really is a great actor. He's charming when he needs to be and he can be deadly serious when the role calls for it. I think he could have been a great Batman AND a great Bruce Wayne. The problem is that Batman & Robin is a poorly written, incompetently directed, cinematic abortion.
Christian Bale: I love his Bruce Wayne, and the fact that both of the recent Batman films have played up that aspect of the character really makes his performance shine. But his Batvoice...he's just trying too damned hard with the Batvoice.