You don't see me picking Marciano over Tyson, Liston, Foreman do you? Looks like the jokes on you :good
I would say he is. Marciano knows how to keep his hands up high, knows how to throw punches in bunches, knows how to punch with leverage and torque, and knows how to bob, roll, duck, slip and weave with his upperbody in his crouch.
What really impressed me when when watching the films of his title winning effort was how Walcott usually only landed his first punch and not his follow-ups. Rocky knew Joe had a nasty kick and made sure that he protected himself against those combos really well.