As a generalisation, when in doubt, i go by whos in the movie. These actors seldom disappoint. And they dont necessarily need to be in the lead role.

Obviously Pachino and de niro (though they both had a few lame movies lately)

Edward Norton
Brad Pitt
Samuel Jackson
Willem Dafoe
John Turturro
William H Macy
Steve Buscemi
Harvey Keitel

oh, and anything by Tarantino