I think Casino Royale and Craig are the best. I have read one of the original Bond books, and it was not only a deep, interesting experience but it felt mostly like Casino Royale. The previous movies have been a fun romp I was always willing to see in the theaters, but they didn't have the same level of sophistication on the plot.
The earlier Bond actors did a good job of playing Bond off as a suave badass, but the original Bond was actually more like Craig plays him, which is to say imperfect but under pressure entirely focused and cunning.
I don't know how Brosnan or Connery would have played Bond had that gotten as good of a script as Craig got, only that he hit it out of the park.