https://www.boxingforum24.com/threads/15-best-h2h-heavyweights-in-chronological-order.720942/ Reusing this list because I'm lazy
Hell, in very, very lose order... Lewis Ali Tyson Usyk Evan Fields Foreman Wladklit Louis (with modern training) Frazier Holmes Vitklit Fury Joshua Bowe Douglas Ibeabucchi Liston Witherspoon Norton Marciano (I'll defend it based on the combo of two-fisted power and stamina/workrate)
It's tricksy to be honest because I think he might lose to Ezzard Charles, for example, but Ezzard Charles is a 185lb fighter with a 73" reach. He's going to get out-sized, bombed-out and he can also be edged out by guys like Walcott and Johnson. So across the piece, no way to include him really I don't think. Spinks has a good chance against everyone despite the one round bomb out. He could edge out Holmes, Charles, Liston, probably too small for the biggest guys but three inches in extra height and reach over Charles and able to carry 210 comfortably just puts him right in the wheelhouse. Sure he'd get caved in by Tyson and Langford, which is awkward, but the bottom five on a list like this are definitely an awkward fit - there are a bunch of other five guys you could select.
1. Tyson 2. Ali 3. Wlad 4. Lewis 5. Vitali 6. Fury 7. Usyk 8. Holmes 9. Louis 10. Bowe 11. Holyfield 12. Wilder 13. Joshua 14. Blond Ortiz 15. Frazier (too small) 16. Ibeabuchi 17. Foreman (not a 12 round fighter) 18. Liston 19. Thomas 20. Ruddock
I think Frazier has a pretty significant shot at beating a lot of guys above him. Peak Ruddock could probably repeat Foreman's best moments and Foreman probably couldn't repeat the Tyson fights, so maybe I have that one backwards.
Because Foreman wasn’t a twelve round fighter. It’s absurd to highly rank a guy who is likely to get stopped or lose a ud while almost collapsing because the other guy comfortably gets past the first five rounds. Frazier matches up better with Usyk, Holmes, Holyfield, ALI, etc.
Likewise Frazier literally never interacted with a hard-punching proper HW other than Foreman, who broke him to pieces twice. And Foreman matches up better against pretty much any big HW that can punch hard.