Meaning in their given and current weight divisions, who has the least competition and least chance to get beaten. I would have to say Wladamir. He has been destroying everyone he faces, and I don't see any plausible or realistic threat to him at the moment. I'm not saying he's the best, obviously he isn't the best fighter in the world, he is up there though and he is fortunate enough to sit on top of one of the weakest divisions in boxing. :deal Here's my list: Wlad - HW Pac - SF Floyd - WW Calzaghe - SM Hopkins - LHW
Also, if Wright does come down to 154lbs he will step into the 2nd or 3rd spot. I really don't think anyone has a real shot at beating him down there.
Wlad - HW Yes Pac - SF no Floyd - WW no Calzaghe - SM definately no Hopkins - LHW not really Hatton at 140
Uh, Casamayor and Julio Diaz? There's no threat to Wlad at HW, no threat to Calderon at minimumweight (although he's moving up for this fight) and no threat to Hatton at 140 (although he's moving to 147 for the Mayweather fight). If DLH stayed at 154, he could rule the roost there as well, outside of maybe Dzinziruk.
IF you asked this question 7 months ago, I would have said Rafa Marquez @ 118. He just annihilated the bantamweight division, and beat the man @ 122 in Vasquez. But now however I would probably say Calderon at 105...though SOlis at 108 (which is close enough to the same weight class for me) would give him a great fight.
Floyd = Welterweight Pac = Junior Lightweight Wladimir Klitschko = Heavyweight Juan Diaz = Lightweight