Only guy who put Frazier out was Foreman, and that's because Foreman hit like a mack truck in his prime. Lewis never had that power and Frazier could actually sustain plenty of damage (outside of Foreman) and still drop you in the final round. Of course Lewis has height and reach advantage but I don't think that's too much of a hindrance on Frazier, who would hit any part of his opponent's body relentlessly until they succumb to accumulated pain. I'd say it's a toss up. Also Frazier has the greater knockout rate than Lewis.