In most sports you can make a damn good argument today's athletes are bigger, faster, and stronger. I doubt many people believe Rod Laver could beat Rafael Nadal. Boxing is a bit different; there are weight classes, a middleweight is still a middleweight, and a poor kid who is athletically inclined has a lot more sports to choose from to make a living thus reducing the talent pool.
I like Ali to win by decision. But Fury’s height and reach would make it harder than people might think.
Tennis is also affected historically by equipment, to a huge degree. The racquets nowadays are chalk and cheese compared to the small headed wooden racquets the Rocket used. Comparatively the racquets from the Sampras era, for example, to now, are much much closer.
I've said this so many times over the years. If anything boxers of the past had much better skills because they had to fight more. They were much more instinctive and creative because of that fact. It's the reason we don't see a Pep , Benitez or Whitaker in today's game. Brawlers like Hank Armstrong or Aaron Pryor. Ultimate boxer punchers like Ray Robinson, Ray Leonard, Sanchez, Hearns, Hagler. Boxing is one of the few sports the athletes have actually gotten worst.
Ali's victories against Liston, Frazier, and Foreman alone were so beyond anything Fury's done as to be near superhuman in comparison. Fury beat (and didn't look great doing it) a 40 year old Wlad. I don't really count that for much. He beat Wilder twice, both times showing tremendous Championship Heart and courage. Good for him, those are fine victories. Was Wilder on the level of Liston, Frazier, Foreman??? Or even the level of the Ken Norton in the second Ali fight? I'm just asking. Fury couldn't beat Ali from 64-74, Foreman pre-Ali, FOTC Frazier...come on. Watch the videos closely, the ones with Ali winning the biggest fights of his career. Fury might have made it the12 round distance with Ali, but that's the best he'd do. Foreman was five times the finisher Wilder was, so was Frazier and Liston. It's not like when he got knocked down by Wilder and Deontay just flailed away Earnie Shavers-like. Those guys were executioners. Iron Mike would have mowed him over. What fight proves Fury could keep up with the above fighters? He never fought anyone near that quality and when he fought the best fighter he ever faced he got knocked down three times.
It's a bit like the Mike Tyson poser, my heart says Ali but the facts are we never saw Ali face a man of Fury's size and skills, for all we know Fury would out Ali, Ali. Pop, pick him off and tie him up, there ain't no way Ali would manhandle Fury like he did all his opponents, it would be the opposite in fact. Wrestling against the bigger man like that would wear Ali out something rotten, the only way to win is to stay on the outside and pick him off, would he be able to do that with a barge pole jab coming straight down the pipe, followed by that new and improved right hand?
Depends on the time frame. 60s Ali treats him in some important ways like he did Terrell, I suggest you watch or rewatch that fight for a good idea of his tactics against bigger men. Yeah, Fury is a better fighter for sure than Ernie, but there's not much reason to believe he'd get the drop on Ali jab-wise, and he didn't hit hard enough to seriously bother Ali. 70s Ali is a different animal in many ways. For one thing, he sat down into his punches more, plus he had off the scale ring intelligence. Though Fury fought a well intelligent Wlad, it was in the twilight of the latter's career, which means he's never fought anyone with anywhere near the ring IQ of 70s Ali. In the 60s scenario, Fury walks aways a UD loser but is fine to fight another day. 70s Ali humiliates him and stops him in 12.