Underrate Joe Louis at your own peril deniers, but the Joe Louis circa Max Baer, and before WW2, would and should be considered the most formidable and lethal punching machine that ever lived, and a favorite in odds over any heavyweight during his halcyon days as heavyweight champion. Sure he had a couple of tough moments in some of his bouts. Louis was only human, but in his glorious prime his coil spring combinations always got the job done and he never had to revert to the "rope-a-dope " to hold off superior punchers as Clay/Ali did time and again. The perfect build for a fighter was Joe, 200 pounds of muscle, perfect timing combined with great balance that should make him a favourite H2H over every other heavyweight ever. I will go out on a limb and say that at his best his most dangerous opponents would be Jack Dempsey of Toledo and the young Mike Tyson ,both who hit hard and fast and EARLY...Joe would have less trouble with the bigger behemoths as he would get their first with the mostess...Of course any top heavyweight of the past has a chance with anyone, but in my minds eye give me the lethal Brown Bomber of the Max Baer fight. And collect your winnings from your bookie...
You simply can't overrate Louis. (or Ali, really, unless you're calling him the p4p and not just HW GOAT)
To me, the two great questions about resume are: 1) did the champion fight the best around? 2) did he treat them the way you would expect a great heavyweight to treat them? You can only fight the guys who are there, and it's theoretically possible that the greatest heavy who ever lived, coming in a weak era, might have a thin resume.
So you are not a fan of longevity? Perhaps you should be. A lot more fighters attain dominance over a short period, than achieve longevity. Hell, if Joe Louis retired after he won the title, he would have been in the mix for that. When you match fighters against the top ten in the division, their failings get ruthlessly exposed, even over a short period. Anybody who achieves longevity against the top ten, is truly exceptional.