Hate to say it, but Daniel Craig. His movies are the best. His Bond isn't a retarded caricature of itself (like Moore and Brosnan). They also give him the right amount of psychopath (his character has an edge). Read a couple of the books and you realize that Bond is not meant to be and action-comedy romp (and is better for it). It's a serious look at a person who has to kill people to do his job. Craig's Bond (and the films) capture this.
Connery's a close second. His character still has a serious element to it, but the films don't hold up as anything other than Bond films. I think Craigs will be seen as legitimate members of the Thriller/Spy genre and not just "Bond." One thing I really appreciated about Connery's Bond was that he was a man. No man-scaping that chest hair.
Moore and Brosnan were suave, but also sleazy. And they films they were in were terrible. "I thought Christmas only came once a year?" They gave her that fucking name just for that one fucking joke! And Moore dress like a fucking clown in one movie. A clown!
Lazenby didn't get enough of a shot. Sad really. He could have been great.
Dalton's an enigma. His films suffer from massive "80's action movie syndrome," but Dalton himself has a really good suave-but-still-gritty look. I think he deserved another go. Dalton's performance raises the quality of the films he was in.