Ali is one of the greatest sports personalities of all time but not the greatest boxer alot of people confuse the two.
I do think tyson was the most gifted heavyweight of all time and could have gone down as the best of all time but never will now, there has never been a heavyweight with the speed power athleticism aggression that wa as elusive and hard to hit as tyson not ali not anyone joe louis was the cloosest
I will not comment on the smaller divisions becuse my knowledge of them is not strong enought to compare them against what i know about the heavyweights.