1. Speed. Mike Tyson was surprisingly fast for a heavyweight, certainly faster than the guys he faced. But, if we’re talking in their primes, and I assume we are, then it’s Ali. He wasn’t just fast for a heavyweight, he was fast, full stop.
2. Power. No question, Tyson was pure power. Even at age 18, he was massive, and his punching power was legendary. That said, Ali was no slouch. He was a big man, who knew how to hit, and he knocked down some of the hardest hitters in boxing history, but it’s Tyson all the way here.
3. Toughness. Yes, these guys could dish it out, but could they take it? Put it like this – Ali was never knocked out in his career. Yes, he got dropped a couple of times, but you never saw him counted out on the canvas. In their first fight, Joe Frazier hit him with a left hook that could have knocked over an elephant, and Ali got right back up. Iron Mike, on the other hand, got knocked out by Buster frickin’ Douglas. A bum. A man Ali would have beat the crap out of. But, to be fair, up till then Tyson did look invincible. His demolition of Spinks is the stuff of legend.
4. Defence. This is interesting, Tyson who stalked his opponents with his peek-a-boo style against Ali who danced with his hands down. But I don’t think Tyson could hit him, at least not as much as Ali could hit him. Ali had this sort of radar – he knew what his opponents were gonna throw before they threw it. You can’t teach that.
5. Final thoughts. What a fight this would be. What a war. But I think Ali’s superior boxing skills would ultimately prevail. I’m not saying Tyson couldn’t hurt Ali. Both times I saw Ali get knocked down, it was from a left hook. And Tyson threw a mean left hook. He might even wobble Ali at times. But Ali’s jab, footwork and handspeed and fabulous boxing brain would overwhelm Mike. Tyson would go for the quick KO, but that ain’t happening. By the fifth round his face would be puffed up and bruised. By the eighth, he’d be visibly tiring. By the ninth, Ali would come out flat footed and just beat the shit out of him. I loved Mike, and wish there were more of his calibre around today, but Ali takes this one.

Opinions from other experts

This is a quandary that’ll be debated forever. The biggest question is which Ali — early 70’s Ali or mid-60’s Ali? Mid-60’s Ali was untouchable, but had an iron chin we didn’t know about.

Then there’s 1988 Tyson. The Tyson that would have a chance against anyone. He wasn’t untouchable but he had an iron chin.

Both were unreal fast but Ali was fast of foot as well as hand.

Ali had the height advantage.

Ali had the reach advantage.

Ali had the heart advantage.

Ali had the chin advantage.

Ali was smarter.

Ali faced far better competition. (The golden era of boxing).

Ali had the psychological advantage.

Ali often fought and trained to his opponents capabilities. Big mistake if he underestimates Tyson.

Hand speed is debatable because Tyson was very fast with those short arms and combos from hell. I don’t think he was as fast Ali.

Tyson had the power advantage but Ali faced much bigger punchers than Tyson.

Tyson ducked under punches and came up at unusual angles — often negating fighters jabs or conventional wisdom but neither fighter fought conventionally.

Tyson was the realization of Cus D’Amato’s style. He was a wrecking machine that could knock ANYONE out at any time.

I think the 1988 Tyson had a good chance against 1971 Ali but zero chance against a mid-60’s Ali who would take away his heart, keep him at bay and knock him out anytime after round 6.