Having said this, you can make a legitimate argument in his favor based on the quality of the opponents he faced. No other former champion’s resume even comes close in terms of the quality of opponents: Liston, Patterson, Frazier, Foreman, Quarry, Young, Lyle, Shavers, Norton, Chuvalo, and Ellis. He fought some of these guys 2 or 3 times. Until he climbed back into the ring at age 38 after a two-year layoff and found out that he was washed up (against Larry Holmes) he was never stopped and won the vast majority of of his fights against world class opponents.

As a young fighter Ali was perhaps the fastest heavyweight ever. Once he slowed down it revealed that he had never developed much of a defense. However, he was tough as nails and mastered the art of boxing to compensate for diminished speed. I would not put him #1 either. But let’s face it, no other heavyweight in history had to face the number of world class opponents that Ali did–fighters that were hall of famers in their own right.

BTW, People knock Larry Holmes for poor quality opposition during his championship reign and on the way up. I deny this. He fought and defeated Norton, Witherspoon, Cooney, Shavers, Weaver, Snipes, and Berbick. On the whole that list doesn’t measure up to Ali’s opposition. However, it is as good or better than most of the great heavyweights. Who did Marciano fight? Walcott and Charles (each twice) and Joe Louis after he was washed up. They were great fighters, but really don’t compare to Holmes’ list as a whole body of work. Look at the lineup of bums that fought Joe Louis while he racked up 25 title defenses. I could go on, but this is sufficient to make the point. On pure skill and the total package, I rate a number of fighters higher than Ali. But in terms of acheivements, it is hard to argue with his record.

1.Joe Louis
2. Muhammad Ali/ Cassius clay
3. Rocky Marciano
4. Mike Tyson
5. Evander Holyfield

P.S. Here’s a blast from the past: Ernie Shavers, remember him ?

1.Joe Lois
2.Rocky Marciano
3.Mike Tyson
4.Muhammad Ali
5.Jack Dampsey

The top 4 is ok, although you could shuffle the order a bit, but Tyson and Patterson make this list garbage.

(based on universal hold of title)
1. Johnson (ranks at or near the top in every category)
2. Louis (most recognized title defenses)
3. Ali (best record against other champions)
4. Marciano (undefeated)
5. Holmes (2nd longest consecutive defense streak)
6. Holyfield (most titles)
7. Ezzard Charles (8 title defenses)
8. Lewis (7 title defenses)
9. Frazier (6 title defenses)
10. Foreman (but this is a precarious rank as he could be replaced by Klitschko eventually)

Dempsey and Tunney fall out of the top due to avoidance of black fighters. Tyson could possible be top 12, but that’s it. He had only 6 defenses and never beat a top champion in their prime as all of the other fighters above him had done at least once.

Sullivan often gets ignored because no one today has ever seen how he fought, but he reigned for 10 years and, although he didn’t defend against black fighters, he did fight several on his way to title and in exhibitions. More than Dempsey and Tunney did, 40+ years later, after times had changed considerably and Johnson broke the race barrier.

Patterson is barely top 20. If that.