CBR is asking this in a poll:
http://www.comicbookresources.com/?page=poll&id=97What are your opinion on this?
Here are the choices CBR included in their poll:
-Bob Kane
-Dick Sprang
-Neal Adams
-Jim Aparo
-Frank Miller
-David Mazzuchelli
-Norm Breyfogle
-Bruce Timm
-Jim Lee
-Greg Capullo
Feel free to discuss others, though, since we're not restricted to the poll options here.
I chose Jim Aparo. When I think of Batman, it's Jim Aparo's Batman that pops into my head immeadiatly. And isn't that what "definitive" means?