I'm not completely surprised to hear that of Liston. Wepner was all broken up facially by Sonny, if I remember correctly. Foreman was more bludgeoning, while Liston had underrated hand speed (and boxing ability).
Fury can't be considered a heavy puncher by any stretch of the imagination. He is a very good, super-sized boxer, though.
If Vitali hit even remotely that hard he wouldn't have so many TKO's/guys remaining on their feet after getting wailed on for multiple rounds. If he had that kind of teeth rattling jaw dropping power his opponents would be on the ground twitching or falling like a sack of potatos. And like you said, far too many common opponents preferring people over Vitali. The only other explanation is either his technique is horrendous or his opponents have some of the best chins in boxing history (lol). I think the simplest explanation is he simply did not hit that hard despite his size. He lacks real snap and explosiveness.
I would doubt Marciano hit harder than Louis and especially Williams. For all The Big Cat's faults, Common opponents rated his power above that of Liston. All three could bang for sure, no doubt.
The closest fighter I can think of who had of frame and style like Wilder's was Monte Munn, who also packed a mean punch and had a similar killer instinct. Knute Hansen and Babe Hunt also had similar frames.
If he punched with the intentions like Vitali did I could believe they hit similarly. Either way I can believe both are levels below guys like Wilder, Wlad, Tyson, Foreman, Shavers, Lewis and even guys not mentioned as much like a Hasim Rahman or a Mike Weaver.
Roy Harris (who fought Sonny Liston and sparred with Cleveland Williams), calls Cleveland Williams his most dangerous and toughest opponent was "when I sparred with Cleveland Williams." http://www.doghouseboxing.com/Ken/Hissner030911.htm "But at one point in his career, he would have spelled real problems for Ali, because at his height as a puncher, Cleveland Williams hit harder than Liston. Before he got shot, the man was awesome But afterwards, he wasn't much of a fighter.. " Source: https://books.google.com/books?id=DfcPAQAAQBAJ&pg=PT134&lpg=PT134&dq="williams+hit+harder+than+liston"&source=bl&ots=U_vhYf34f8&sig=ACfU3U0-9tFME4JqtaE-xx34tjfj1d-8XA&hl=en&sa=X&ved=2ahUKEwiqlYTguIHqAhUeRDABHQPoDhYQ6AEwAXoECAMQAQ Ernie Terrell (Who fought Williams twice and sparred with Liston) His toughest opponent: Cleveland Williams https://news.google.com/newspapers?id=-pleAAAAIBAJ&sjid=vVINAAAAIBAJ&pg=4798,539251&dq=&hl=en :"He was the strongest fighter I ever fought" http://www.thesweetscience.com/news/articles/6048-ernie-terrell-chicagos-heavyweight-champion "His left hook is poison." https://news.google.com/newspapers?id=Sy8_AAAAIBAJ&sjid=9lAMAAAAIBAJ&pg=3337,4585601&dq=&hl=en "I fought Williams (Cassius Clay's Monday night victim Cleveland Williams twice and I thought that man hit harder than even Liston. But the years were very much on Clay's side." Source: https://www.newspapers.com/clip/57503132/calgary-herald/ Sonny Liston:......"Williams hit very hard and he was quick" "He hit as hard as I could." https://books.google.com/books?id=9...hUKEwjz2eGWs7XpAhWIg-AKHZlGCKgQ6AEwAHoECAoQAQ "two of William's losses came at the hands of Liston, who has said Williams was the hardest puncher he has ever met." https://www.newspapers.com/clip/51090697/sioux-city-journal/ "Williams hit Liston with a left hook that would have finished any other man It would have torn some fighters heads off." https://www.newspapers.com/clip/54152307/fort-lauderdale-news
When Foreman mentioned the hardest punchers he's fought/sparred he never mentioned Liston but he did mention Cleveland Williams.
I'm deeply confused now. Muhammad Ali maybe would know better, but as Cleveland William couldn't even land a jab at ali, we would probably never know.
We will never know for sure, according to a boxer that fought Marciano and Williams he said Marciano hit harder and most people say Williams hit harder than Liston, so Marciano has to be one of the hardest hitters and definitely hit harder than both right? BUT then Archie Moore comes out and says Curtis Sheppard, Lloyd Marshall and Yvon Duerelle hit harder than Marciano, crazy right?
If the question is “who hit the best fighter as hard as he could” Then wilder falls behind most all time greats.