There have been five men to portray Batman in the character's eight live-action feature-length films, from Adam West in Batman '66 to Christain Bale in 2012's The Dark Knight Rises. All five actors came with their strengths and weaknesses, but the best was Michael Keaton, who played the DC Comics superhero in 1989's Batman and 1992's Batman Returns.
In the first major scene of Batman '89, Keaton famously grabs a terrified mugger by the collar, holds him off the side of a building, pulls him close to his face, and hisses, "I'm Batman." As a 12-year old watching that moment on a VHS tape in my living room, I believed Michael Keaton. And I still believe him as a grown man watching it on DVD in my office 25 years later, even after having seen a half-dozen different Batman movies since.
I realize declaring Michael Keaton's performance as Batman to be not only my favorite Batman but the best Batman is a somewhat controversial statement, even (especially?) among my fellow writers at ComicsAlliance, but allow me to make my case.