Tszyu. Absolutely no doubt in my mind. A faded, inactive, post-injury Tszyu was able to basically go tit-for-tat with the best version of Hatton - and IMHO legitimately drop him with a body shot. Vs. a prime Tszyu? Hatton wilts and either gets stopped by accumulation or loses a clear decision. Peace.
I like Hatton more than I ever liked Tszyu but still, the Tszyu of 98-99 would have busted Ricky up and stopped him. He was alot quicker back then both of hand and foot, had better reflexes, and was alot meaner than the old washed up pussy Tszyu that Hatton beat in 2005, and STILL Kostya was competitive. Prime Tszyu TKO 9 Hatton.
I think Tszyu must've felt he had nothing left to stop Hatton in round 12. And being in Manchester, there was no way he was going to win a decision (not that I thought he should've been winning anyway). I agree that a sharper, quicker Tszyu would beat Hatton.