This is a question that everyone has an opinion on. The fact that I can't abide James Bond does not stop me from having an opinion.
For the sake of simplicity I'll be sticking to the main movie cannon. This sadly excludes Bob "Blockbusters" Holness from consideration. Likewise David Niven is gone.
So the candidates are:
1. Sean Connery.
For some reason considered the "definitive Bond" by many, presumably because it is apparently Gay to think of anyone else as the best Bond. Unlike Luke I am secure enough in my hetrosexuality to call bullshit on this. Connery's bond is not so much dry as arid. I cannot imagine him existing outside of the confines of the stories in which he inhabits. He is truely two dimensional and not in an "iconic way". Factor in the fact that Connery is clearly now in a competition to become the living "breaveheart" whilst simultaneously trying to out insane Mel Gibson and becoming the poster child of Domestic Violence and you can see why I would rather watch the grass grow than watch him as Bond.
2. George Lazenby.
Does he even count anymore? Even McGann has had a better run as Doctor Who than this joker had as Bond.
3. Roger Moore.
Appears to be as sound as a pound and a top bloke in real life. Brought some humour and levity to the role. I can watch his Bonds without wanting to gouge my eyes out. Now that's not to say that I enjoy them (I don't) merely that his portrayal is such to justify the films existing.
4. Timothy Dalton:
Took a "serious" approach to the role. Thereby showing that he had missed the point entirely. Bond is a tedious schoolboys fantasy. If done in the right way though (ie the Roger Moore way) there can be some fun and enjoyment to be had from this rather limited character who basically only ever experiences one sort of story. He did at least have the right colour hair and also doesn't seem to think he is the King of His people.
5. Pierce Brosnan.
I can remember me (and plenty of others) being adamant that he was perfect for the role, bron to play bond etc. Its a measure of how shite an actor he is that he is dreadful in the role he was born to play.
6. Daniel Craig. Haven't seen him. But plenty of Bond fans I know aren't impressed. Moreover he seems to be following in Dalton's footsteps.
In conclusion. Roger Moore was the best by virtue of the following:
1) Being the least worst Bond.
2) Being in the least worst films.
3) Being a decent guy in real life.
Also just to re-iterate, Sean Connery is an arse.