Muhammad Ali and it's not close
Edit: anyone who disagrees, go watch his fights lil bro, anyways I'm off to sleep
Yea but he was still more dominant compared to 2nd in his own sport
And actually swimming and boxing aren't too popular sports , as far as I have seen both are equally popular or swimming is actually more popular
Even if boxing was more popular , Micheal Phelps literally won more medals than 90% countries
Ali has competition for best boxer of all time. That does not put him the GOAT athlete debate.
You have to be the best at your sport to be considered.
With ESPN using science to grade out how difficult it is to be at the top tier of sports https://www.espn.com/espn/page2/sportSkills
Its Wayne Gretzky and its not close.