Tszyu by late stoppage. Cotto improved greatly when he moved to 147 - at 140 he didn't use his jab as effectively and was more reckless. He was very aggressive back then and was more dedicated to his body-attack. I think Tszyu would turn that aggressiveness against him, catching him with that straight-right whenever he tried to force his way inside. Cotto seemed easier to hit at 140 which is bad news against an accurate power-puncher. Also, before he refined his style, I think Cotto was less adept at fighting outside. Back then, he was all about getting inside and punishing his opponent to the body. He fought more often at mid-range and someone with Kostya's timing and accuracy could take advantage of that.