The NFL is unwatchable particularly in person. 20 seconds of action followed by : Penalities (for anything short of breathing), injury timeouts, challenge reviews, TV timeouts, regular timeouts, 2 minute warnings. It's pretty much the worst entertainment for the dollar. Most fans attend games for the tailgates, which start many hours before kickoff. By halftime everyone is exhausted from drinking and having to sit through so many stoppages.
Oh and yeah I know the NFL is the most popular U.S. league.