Going with Jack Dempsey here. As much as he is a American boxing fan favourite, he isn't literally walking through and one punch KO'ing anyone, especially with that awfully crude boxing style. He ducked several fighters & most of his opponents were cherry picked. Jess Willard was an oversized, obese and dimwit human punching bag having no idea how to use a jab, and people assume that just because Dempsey beat the above mentioned guy he'll automatically walk through a modern, highly skilled and very powerful SHWs like Lennox Lewis, the Klitschko brothers to name a few. But his historical status and what he contributed to the sport cannot be questioned.
Can't say I can agree with all your points but I'd agree on it being Dempsey...... far too much nostalgia. People saying he'd beat the likes of Lennox, Fury etc are living in dream land.
I would say that you have it the wrong way round. He was a head to head monster, and very obviously so, but it is easy to pick holes in his resume.
Mike Tyson? Hey, he's not terrible H2H but the fact that some (quite a lot actually..) people think he could easily steamrolls literally EVERYONE including elite fighters such as Holyfield, Lewis and Holmes in his prime with his beloved trainer Rooney is very absurd. Prime Ali is also slightly overrated H2H beast. Peak Ali only steamrolled old Patterson, ancient Liston, shot Williams and 100 year old Folley. You put all those performances in one video and "BOOM" you have the finest Muhammad Ali highlight reel posted by Reznick (titled: Muhammad Ali in his prime - Blinding Speed). You see, Ali would beat almost heavyweight no doubt BUT he can't easily steamroll through all of them easily. When Ali fought real fighters who are in their prime he doesn't put up that godlike performances as shown in the reznick video. Doug Jones went back and forth with him, Mildenberger put up helluva fight till he gets knocked out and George Chuvalo drove Ali to the ropes. Terrell performance against Ali was simply terrible, no hate on Ali but Terrell straight look like sh*t. He wasn't himself, throwing 99.9% jabs than he used to and finished up the fight just by shelling up the whole entire time. I remember a guy said Mike Tyson can't even touch Ali becuz he is in a league of his own. I was like, ARE YOU F*CKING KIDDING ME!!?!??!
Possibly Monzon at 160. Obviously an outstanding Middleweight (I have him #1 there in terms of record and achievements, so there's no axe to grind) and almost certainly a champion in any era. But I think his dominance 1970-77 over-inflates his standing head-to-head just a touch. I think a few of the names on his record were tailor-made for him styles wise and going beyond 160 I'm not sure his style would have translated too well into the Super-Middleweight division and some of the titlists who have operated there.
Joe Louis no doubt. He lost against most greats at least the first time around. I see him getting beat by most champions before and after. Patterson and Louis would have been a great fight.