I've already said Timothy Dalton was a very underrated Bond. Also, George Lazenby was pretty decent, that movie was just ruined by Telly Savalas as Blofeld (which was sacrilegious after Donald Pleasence's portrayal) and the incredibly depressing ending.

Also, Sean Connery's Bond is quite different to his other roles, and he defined Bond so well, he was (and is) the best.