All time comparison: Joe Frazier & George Foreman

Who do most people have higher in their list of all time best heavyweights of all time. Please give analysis about why you have one ranked over the other. Also, regardless of who you have higher on your list, how does Foreman's return to boxing, where he recaptured the heavyweight title by knocking out Michael Moorer change George's place in history? I realized that, somehow, I don't think I've ever seen a debate on this subject in my entire time as a boxing fan. I just saw a list of best heavyweights of all time that had Frazier higher than Foreman, which made me wonder who most people have higher? I would have thought Foreman, as he obliterated Frazier when they fought, and came back to have a successful second career; plus, his only losses were to Ali (who Frazier lost to) and a loss to Jimmy Young that most people seem to excuse. By the way, that list had Marciano as #1 all time, so I didn't put much stock into it, but I am curious about what you all think anyway.