I don't think these records really mean anything to begin with, the fighters have their own legacies. Marciano is remembered because he retired as the undefeated HW champion of the world, it's not about his 49 fights, he only had a few good opponents and title defenses! Wlad has to be given some credit for reigning as HW champion for a long period of time, as only a handful of others guys, Louis being one of, have done. Floyd has done something massive in his own right going undefeated(or at least never being badly beaten) over so long in multiple weights. He probably has almost as many truly good fighters on his resume as the other 3 guys in this thread combined imo.