Muhammad Ali: Great or The Greatest
Ali, in the end, said the whole talk about him being "the greatest" was all hype, but if you look at all of his assets, perhaps he was.
- Longevity. He essentially had two primes.
- He was easily the fastest moving heavyweight
- He competed in the most competitive era in history.
- He never cherrypicked. He faced all of the toughest fighters.
It's hard to objectify this, because there are differences in eras (the nutritional and training standards) as well as weight classes.
But Ali is a very good candidate for the #1 spot.