It's a toss up between Craig and Connery.
Connery made the role famous and defined it.. he's the first Bond and had some of the most iconic movies in the franchise.
Craig is very different partly because the movies are so different. The reboot was in dire need and so the focus shifted from mainly babes, gadgets and over the top villains to a more down to earth style and Craig played that part really well because he looks more like a bruiser than a gentleman.
However when he put on the tailored suit before the game in Casino Royale my eyes popped.. somehow he managed it to make me believe he always was destined to wear such attire. That's good acting and so i'd rate him as the best.
Brosnan (perfect for the role and played it well, to bad his movies were shit scriptwise)
Dalton/Lazenby - equally bad