in many aspects. Passion, extremely loyal fans, historic, standing instead sitting watching the games, 100% team oriented. All rivalries are true rivalries. NFL is league -oriented. Each team in the league, just like a McDonald, is a franchise. The league can move the team here or there. There is no true long term rivalry except perhaps Green Bay with Chicago/Detroit.
But with that being said, overall, American football is the best sport in the world. American college football is the best "league" in the world.