I had to vote for Keaton. He's just IMHO the closest to the comic book character, or the one portrayed in the later comics. All of the others are too chatty, and just don't seem to fit the role.
I do think Clooney would have done well if the script hadn't stunk so hard. He's got that mysterious aura, but he just talked too darn much, and the story was horrible to me.
I think my favorite Batman portrayer is Kevin Conroy; who does the voice characterizations of Bruce Wayne in both the animated series from a couple of years ago and Batman Beyond now. I know, he's not doing the physical stuff, but his voice fits so perfectly!
As I said in the other thread, I'm all for giving Michael W. Weiss a chance. He's constantly dark and brooding in his tv show, and does the tortured character thing well.