Butterfly, because you seem very young and ignorant, I'll let your "Ali is the greatest because he said so" argument pass.
First let me make this very clear to anyone reading: I feel Ali was one of the greatest heavyweights of all-time. There is no denying this; however, it bothers me when uneducated kids come on here and say he was unbeatable and unstoppable, he would "dance circles around (insert all-time great)..."
Muhammed Ali, or Cassius Clay, was in trouble against Doug Jones in 1963, a fight for the right to face Champ Sonny Liston. Jones wobbled Ali in this fight, a couple of times.
Also, in the fight IMMEDIATELY preceeding Clay's beating of Liston, little Henry Cooper (183 lbs) dropped Ali in the 4th round. Ali was in queer street and his trainer, Angelo Dundee might have saved the future-champ from a stunning defeat by ripping his glove while in the corner, thus ensuring Clay enough time to recover. The fight was stopped on cuts on Cooper the next round.
Even after Ali's prime, he received gift decisions against Norton and Lyle, to name a couple. Ali always received a little extra from the judges because of his name.
He was supremely talented, but his skills were somewhat lacking. He held his hands too low (knowing he was a much better athlete than a lot of the plodders he fought in the 1960s) pulled back at punches, and also used illegal holding quite a bit in his later career.
Against someone of similar athletic skill, he would be in trouble. He always struggled against pressure, swarming-type fighters. This style gave him the most problems.
And as for handspeed, I can think of a few heavyweights with similar handspeed. Mike Tyson, for example, actually had quite comparable handspeed. What makes prime Tyson's handspeed more impressive though, is that he threw POWER punches so quickly...Ali's flicking jab and right were very fast; however, Tyson's right to the body, followed by an uppercut was more impressive...he sat on his punches and delivered them nearly as fast, if not as fast as Ali delievered his.
Ali is overrated because so many uneducated young fans think he was absolutely unbeatable and had no weaknesses...he did. He is a top three heavyweight of all time, in my opinion; perhaps #1, sometimes it is difficult to decide. However, I dont engage in mindless worship, I have the ability to watch his fights (and have seen damn near every one) and see strengths and weaknesses.
Just because some says they are the "greatest" often enough, doesnt mean that they are, without question, the Greatest.