P4P is should be Duran, if for no other reason that Ali, much like Lewis, was significantly bigger than most of his opponents, also since Ali was a heavyweight he couldn't go up in weight classes, which of course Duran did. Finally Duran is a much better fighter technically than Ali was. Ali was somewhat similar to Roy Jones in that he was a superb athlete, but was technically flawed. For example Ali would move straight back, never threw body punches, and relied on his ability to absorb punishment in the later years, rather than defense. But I'd probably give the edge to Ali in terms of his comp.
Duran fought in 5 different decades and won titles in 4 weight classes and is the GOAT at lightweight .
Ali is a top 3 atg on any respectable atg list. Duran is never rated that high. Ali isn't considered the goat for no reason. Btw this poll should've been public.
I personally agree that Ali is the greatest HW ever, but there is a significant faction that exists making the case for Louis.
Based on resume and skill and contribution to the sport Duran couldn't carry Ali's spit bucket. :deal Ali is arguably the most known man on earth.