I think mike gave the ultimate definition of American sports - explosive. If it doesn't happen inside 5 seconds, the crowd gets bored... ;)

I'm biased being a Brit, but I'd say rugby. In rugby you have to keep doing it. Over & over & over. There're no time-outs, no substituting the offensive team for the defensive, no armour to reduce the impact. 80 minutes of barely legalised warfare...

I would love to see a round tournament (if you could work out an equitable rule system) of AF vs. RU vs. RL vs. GaelicFb vs. ARFb. I strongly suspect that AF would come last - they're too specialized to be the all round athletes that the other disciplines require.

I reckon it'd come down to an interesting fight (possibly literally!) between ARFb, RU & RL.