Conroy. Everything about the animated series was definitive of what a Batman story should be on any type of screen.
Keaton was good. I think what he excelled at was playing Batman, but also having Batman spill over into Bruce Wayne. Maybe it's just me, but I think Bruce Wayne would be a little weird in his everyday activities. I mean, let's face it, anyone who does what he does is a total weirdo.
I think Bale needs another movie or two before he makes the role his own. Not to say his performance in Begins was bad, it was actually quite good in my estimation, I think it just didn't have some subtle nuances of the character. I think he has a great opportunity to really hit it out of the park in the sequel.