If one looks at the fighters Ali beat and fought, then he...

If one looks at the fighters Ali beat and fought, then he eclipses Marciano and Tyson by a country mile.
Maricano and Tyson have parallels with each other.
Marciano only had 8 title fights and 2 of them were against Jersey Jow Walcott who was 38 and 39 for the 2 bouts.
Joe Louis was 37 when Marciano fought him and Ezzard Charles was 33 for the 2 bouts.
Tyson faced a lot of boxers past their best and was kept away from Holyfield and Lewis in his prime.
He fought decent fighters only when he was no longer the main attraction and the undefeated meal ticket status had long since dissappeared.

Ali's fight list is a virtual whose who of the best era on record.
A lot of the fighters Ali won or lost against would have wiped the floor with Maricano and Tyson.