I just watched a bit of an American football game, New York Giants against Detroit Lions. I know nothing about American football except what Charles Sures once told Paddy and me way back in 1989 at the Objectivist summer school in La Jolla: it's all about territory.
At a first glance, American football looks a lot like rugby - muscle-bound scrums, running with the ball, rough tackling, trying to carry the ball over the line. Rugby players, however, look nothing like football players. Rugby players look battered: broken noses, cauliflower ears... features coarsened and blurred by repeated trauma over the years. Football players look well cared for: some faces sharp-featured, others with smooth curves and planes, all unmarked by injury. Rugby players do not wear helmets. Football players wear helmets (and shoulder pads, and gloves).
Football players also seem a bit taller and more slender than rugby players. I don't know if they really are, or if they just look that way because they wear skin-tight breeches instead of shorts.
My verdict is that, on aesthetic grounds alone, American football beats rugby hands down. Just to be clear: football may or may not be better in other respects (I suspect it is); but it's already better enough in the way it looks to be better overall than rugby. And isn't it just a bit dumb for rugby players not to wear more protection?