While Sean Connery did an excellent (and perhaps the longest running) Bond role, I think Pierce Brosnan has superceded him by far. To memory, there hasn't been a better Bond before him. Pierce naturally possess vicious grit, suave tenacity and delicious english debonair... to the point where his improvision in the recent films is nothing short of absolutely brilliant. Pierce is a tough act to follow...
...which is why I think:
1. Choosing any old actor (esp. an unknown) is a bad idea - It would be akin to the hiccup that was Timothy Dalton - arguably the worst Bond yet.
2. Choosing any old Scottsman won't do either. McGregor doesn't have the same kind of grit as Brosnan. It would be a step down. He can't convey antagonism as fiercely as Brosnan. He doesn't even have the same depth of tone in voice. McGregor would be an impossible sell.
3. Law neither has the ubiquitious Anglo-Saxxon facial structure nor the hair (the hair is EXTREMELY important!). He has the debonair and the suave personality, but no grit whatsoever. He would make a pansy-*****ed Bond. He's a better fit than McGregor, but still a hard sell.
4. Jackman doesn't seem to have the debonair to convey the same marriage of deadly silkiness of Bond's personality. Jackman is typecast into more guns 'n glory type of roles. The Austrailian aura is not beffitting for an intense english role either. He has the hair, but I won't swear on the face - even though Australians were English people.
...that leaves us with only one choice:
Clive Owen.
He's got the debonair demeanor, the suave personality, the right amount of vicious cynicism in his portrayals (see BMW Films), the hair, the face, the posture, the eyes... and most importantly, a NATURAL english accent to convey the texture of deadly silkiness.
When I think Bond, I think of an actor who could comfortably replace, if not outdo Brosnan. Clive Owen comes closest, I think, to all of the requirements of an updated Bond. In a selection like this, look and feel are everything.