Moore pretty clearly. Simply beat the better fighters, and is one of the few who who clearly surpass Mayweather in terms of longevity. He's got more losses, but he's also got like 10 wins that are better than any of Floyd's outside of Pac. Plus like, something like 30-40 more wins over rated opposition than Floyd does. His depth is insane. Having the all time KO record (I don't recognise that Billy Bird mfer) doesn't hurt either.
Mayweather. He was the top dog of a decade and a half span. Mayweather beat Canelo, but Moore didn’t beat Marciano.
Mayweather is levels above Moore, not close. Anyone want to try and argue a skillset Moore had over Mayweather? Mayweather would have probably shut out the Burley who dominated Moore too. What happened when Moore fought elite opponents in Burley, Charles and Marciano? The only argument for Moore over Mayweather is he may have beat Floyd with 30-40lb on him. That's believable. Otherwise P4P Moore is levels below