1 or 2 probably. I don't really believe in absolutes when ranking ATG's. It's hard enough to know what is going to happen with any certainty with people in the present against their peers nevermind across generations. Safe to say he is topshelf.
Bad choice of word on my part about the prison thing but the point I was making was that 3 years of his youth was taken and he still came back and beat top fighters in their prime. My fault for the wording . Thanks for the link too.
It' all about the quality of opposition you beat. Ali has beaten three Top 10 ATG heavyweights - Liston, Frazier and Foreman. No other Top 10 fighter can boast anything like that. For that reason Ali is the greatest. And it is unlikely he will ever be surpassed.
In terms of ability, he's arguably the best ever. A lock for top 3. In terms of overall greatness, probably around 6-7th.