For his resume, the Mosely fight did the most for him. The Torres fight was his most admirable win, IMO. He faced a persistent slugger and somehow pulled it off.
Shane Mosley...without it, he would have zero wins over future hall of fame fighters. I highly doubt he'll ever secure a victory as big as the Mosley one.
I say it was against Torres. He had to really battle adversity in that fight and dig deep to get the victory. I feel against Mosley he had a relatively easily fight.... especially compared to his wins against Judah and Torres where he absorb much more punishment.
He beat Shane Mosley by one or two points, and that's his best win so far. Mosley has been asking for a rematch ever since, but Cotto never wanted it.