Clottey has been criticized to death for having stamina issues and breaking down late in fights. My references are his fights against Margarito and Cotto.
Though I haven't seen too many of any of their fights, I would give the nod to Clottey. Berto is an exciting fighter don't get me wrong, but sometimes he's too aggressive when he doesn't have to be. I believe it was last year he had a fight in which he was swinging for the knockout against a formidable opponent(can't remember who it was) and he got rocked and knocked down! He eventually won by decision, but if he fights Mosley like that and I think he will HE WILL GET KNOCKED THE **** OUT!! Clottey on the other hand is a very good, and patient fihghter!
The resume perspective. Berto's best win: Razor thin controversial victory over Luis Collazo Clottey's: Decided victory over Zab Judah w/ claims to fame from controversial loss to Miguel Cotto