American football. Not because the actual game is boring, it isn't. There's just far too much time fartin around. Considering plays last on average 20 seconds and the play clock between is 40 seconds and every single stoppage cuts to some bastard trying to sell me shit, I quickly lose interest.
Canadian football is way better, shorter play clock, one less down, more turnovers and riskier plays. It's not possible for teams to grind out territory five yards at a time then fuck the dog for half a minute in between.
Trouble is that Canadian football has like five teams and they all get a prize.