The winner, and five-time heavyweight champion of the world, Muhammad Ali!
Mike Tyson was a bully in the ring. His opponents feared him, and the smell of fear was like chum in the water for a hungry shark. The first fighter who, for personal reasons, was too distracted to be afraid of Tyson, was Buster Douglas. Buster Douglas kicked his ass. I watched that fight live, and it was a massacre.Ali is not going to be afraid of Tyson, and with his taunting, he'll have Tyson completely out of his mind by the second or third round. Ali stopped Joe Frazier, who wanted to kill him. He knocked out George Foreman when everyone thought Foreman was invincible. He psyched out the original unbeatable monster, Sonny Liston.
Tyson was never trained properly to go 10 rounds, much less 12-15. The longer the fight went, the more dominant Ali would become. My guess is that Cus D'Amato stops it, much like Eddie Futch, when a mostly blind Tyson is getting his head ripped off with punches he can't see.
Skillwise Mayweather was easily the better boxer. Tyson was all about aggression and raw power. In his early days he was more an inside fighter, and he turned to a brawler. A good outboxer could have stopped him without sweating too much and that's exactly what Holyfield did. Discipline counts just as much as talent. Tyson seemed mentally to collapse when Cus D'Amato died. Mayweather has gone into his fights in top shape, with no meltdown period like Tyson. Nor did he come into fights fat and out of shape like Muhammad Ali in the late 1970s.