Pep, Duran, and Jofre are notable omissions on your resume-based list, and from what we can see of them, they are clearly great fighters by any standard.
I could never forget Robeartoe, he's probably my fave fighter of all-time. He's got arguably the best single W in boxing history and copped a serious EVT over Hagler.
There he was several years off his best at a far less effective weight where before you've even seen him fight cuts a relatively unimpressive figure: Then you do and it's revealed he has unequivocally diminished attributes, ability, will to fight, and even worse, lesser motivated training habits than before when he had the surprisingly fast hands, cat-like reflexes, greater agility and fluidity in his defensive upperbody movement, fresher wheels, higher level of stamina, a more consistent work rate and if not more power relative to the divisions then certainly a higher capacity to get his shots off and find the target.
The multitude of angles Duran was able to attack, slip, roll, duck and counter effectively from just isn't even comparable. It's a wicked reality of what were looking at here as compared to a 135-147 Duran who'd put everything together circa mid-70s and culminating in his historic triumph over a primed, undefeated Ray Leonard.
Still, he went in with the highly capable, highly conditioned ambidextrous Top 5 ATG Middleweight who was right in the thick of a seven-year, 12-defense reign at the top and basically operating right near the height of his powers. What happens? He doesn't just last the distance with him - something every other Hagler title challenger aside from Ray Leonard failed to do - he fights competitively, he wins rounds, and at times makes him look tentative, ordinary, even puzzled by not fighting in the manner that on paper should've afforded a natural counterpuncher like Hagler the chance to look dominant and impressive in what up to that point was considered the biggest fight of his career.
I hate doing lists, and determing rigid criteria is tough: Strictly Resume? Resume + Ability? Top Wins + Ability? Isn't it actually ability/skill that determines the quality of fighters
on a resume? Does the level of dominance or career longevity play significant factors? How much weight does successfully running through multiple divisions carry? Always felt boxing fans had the liberty to emphasize whichever aspects they saw fit, so long as it can be intelligently argued and done with some level of consistency across the board.
Matt McGrain's was a pretty solid template for at least attempting to rank the greatest boxers since SRR though:
01. Muhammad Ali
02. Roberto Duran
03. Sugar Ray Leonard
04. Pernell Whitaker
05. Roy Jones, Jr.
06. Carlos Monzon
07. Eder Jofre
08. Marvin Hagler
09. Julio Cesar Chavez, Sr.
10. Emile Griffith
11. Jose Napoles
12. Floyd Mayweather, Jr.
13. Manny Pacquiao
14. Alexis Arguello
15. Michael Spinks
16. Thomas Hearns
17. Bernard Hopkins
18. Carlos Ortiz
19. Fighting Harada
20. Ruben Olivares
21. Evander Holyfield
22. Salvador Sanchez
23. Wilfredo Gomez
24. Vicente Saldivar
25. Dick Tiger
Muhammad Ali's best wins, resume depth and peak ability are extremely hard to argue against although I feel both Duran and Leonard were better fighters and the only two with any true argument here. Pernell is one of the five best fighters I've ever seen on film to this point and (I believe) has the best resume of anyone since SRL capped his legacy with the Hagler win in '87. It goes without saying that I consider Chavez a clear win and I scored the De La Hoya bout - who was #2 P4P - 114-112 in his favor. This can change things quite dramatically, see. Even without Oscar...
Mike McCallum was a (huge) snub here for me as I consider him the greatest Light Middleweight of All-Time (albeit brief history) and had him taking the second fight against a prime middleweight James Toney pretty clearly whilst past his own best and consider Sumbu Kalambay one of the Top 10 defensively skilled fighters of all-time, avenging a previous defeat against a stylistic nightmare.
He also wiped out an undefeated Julian Jackson and holds wins over numerous other world-class technicians (Donald Curry, Herol Graham, Michael Watson). He's got couple losses, but the level of formidability in his opposition and win column is quite amazing tbh. He was passed over for fights with both Thomas Hearns and/or Roberto Duran at 154 in the mid-1980s who stood to make more coin fighting eachother.
