Might have to give that one to Tua. Obviously prime Mike would wallop Tua, but 97 Mike... I don't think his heart was in it and he had so many demons at this time.
Tua, by contrast, was 6 years younger, fresher, and would have been 100% motivated for such a mega fight. Tua showed he had the durability and stamina to stay in the trenches (Ibeabuchi fight) and maintain his power in the later rounds (Izon, Maskaev).
So if I had to bet, I would take a prime, full of piss and vinegar Tua to stop the coke head shell of Tyson in the later rounds.