I'm asking you to justify picking Floyd over the fighters on that list based on accomplishments. If you're going to give me the "he never lost" argument, spare me. Nobody cared about that in boxing until Floyd became a PPV star. You don't subtract from wins just because you lost.
Don't have time for that. You're in the minority for just creating some big list that isn't in agreement with what boxing people are saying and without even arguing why. Like Lewis existed at the same time as Floyd and was more lightly regarded. He also got his bell rung twice during his prime. That's just one example.
The main problem with Floyd is he never really has to overcome adversity. For example l don't recall many, if any, fights where he was the clear underdog going into the fight and found away to win.
I don't think there is an educated consensus on Mayweather's ranking. I personally know the resumes of the vast majority of those boxers, and some of the really old time boxers that make up the top 10-15 which I don't know of in depth appear on almost every top 100 boxing list you can find. You mention Lewis. Lennox Lewis beat: Evander Holyfield, an ATG P4P and ATG Heavyweight on his own, who dominated Cruiserweight and beat Tyson at heavyweight. Beat Tyson himself. Tyson was past-prime but still able to knock out top contenders. Tyson is one of the greatest Heavyweights of all time. Vitali Klitschko in his prime, who along with his brother dominated heavyweight for years after this loss and would never lose again. Lennox was past his own prime at this point. He got KO'd twice, it's true; something much more likely to happen at Heavyweight than any other weight, because everyone can punch. And he avenged both of those losses. Few fighters can say they beat every man they fought. Floyd can, but Lewis had to face the adversity of losing to do so. Then you have contenders like the KO artist David Tua, an undefeated Michael Grant, Razor Ruddock, Andrew Golota, Shannon Briggs, Ray Mercer, Tommy Morrison. He beat them all and knocked out most of them. The man was the undisputed king in a stacked division. It hardly gets more dominant than Lewis. So, yeah. While Mayweather has ATG defensive skills, great depth, amazing consistency, championships at several weight classes, a superb IQ, and great versatility, his wins fall short. Pacquiao De La Hoya Cotto Corrales Castillo Hatton Canelo A past-prime Manny Pacquiao stands out on Floyd's records. A prime Holyfield is better. Knocking out a past-prime Mike Tyson is more impressive than a competitive decision against an old De La Hoya. Stopping a prime Klitschko past Lewis's prime while getting old himself is better than a decision over a worn Cotto. Corrales, Castillo, and Hatton are of a middle tier not found on Lewis's resume, but Ruddock, Morrison, and Grant aren't far off in terms of talent, if not resume. Canelo, at the time Floyd fought him, compares to many of the top contenders Lewis fought. Young and dangerous with not a whole lot of experience. So, as you can see, my argument is not without merit. This is not because Floyd isn't great, he is. But plenty would put the last Undisputed Heavyweight Champion Lennox Lewis above Floyd Mayweather Jr., and for good reason.
But surely it's relevant that he never lost and many several of the fighters you listed lost to fairly unimpressive opposition? And even by your very narrow criteria, how do you compare the accomplishments of a man who moved up through 5 weight classes to take on bigger beltholders and ranked contenders to someone those spent their whole careers in one weight class, let alone those whose biggest wins were against smaller men?
The "5 weight class" nonsense is a modern entrapment. In truth, Mayweather only fought a 20 pound span of 130-150+ Historically that is only about 2 divisions, Lightweight and Welter. Ezzard Charles fought the best in a 40 plus pound span of 160-200+. In his time that was only MW, LHW, and HW. But in modern context that would be MW, SMW, LHW, CW, and HW. Langford fought a 60 pound span 140-200+ opponents. That is 8 modern weight divisions! Willie Pastrano, a low end Hall of Famer, fought an 80 plus pound span from 120-200+ opponents, peaking with a Light Heavyweight Championship win over fellow Hall of Famer Harold Johnson. His career spanned 12 modern weight divisions! Should I continue how puny this 15 pound 5 division claim is in a historical context?
Mayweather spread 49 fights out over 18 years. He stayed in shape and won all those fights, to his credit, but I don't think it is comparable to those fighters of yesterday year who fought a much busier schedule and didn't always have the advantage of picking and choosing when and who to fight. It also seems that in the modern age, world titles are created all over the place to give decent contenders inflated status.
So you're gonna chop Floyd's resume down to that? First off, those are better than Lewis's best wins, but you left off two hall of famers and a first ballot future hall of famer for starters. In other words, you left off as many hall of famers from Floyd's resume as Lewis has on his. Think about that.
And the men you mentioned receive rightful credit for their accomplishments. But even in historical terms, no reason to disparage the span of Mayweather's career, from fighting well under the lightweight limit to fighting men who were too big to be welterweights. Especially when being compared to one-division champions like Hagler, Monzon, and the heavyweights.
Canelo was 166 for Mayweather. Also have to factor Mayweather dehydrated to heavier weights. So 3 sounds about right on traditional scale. Funny, imagine Canelo having to mix it up with the historical light heavies who came in non title bouts over 180 and were used to mixing it up with 200 pounders. I think Canelo would likely campaign at middle.
I only insist the comparison be fair. The 5 weight division thing needs proper historical context. Some posters, not you, try to use that as an ace play to argue Mayweather over the likes of the fighters I mentioned.