Hockey... thats a fun sport to watch, because it's rough but it flows and if you're watching two good teams, the balance is pretty decent. I don't like sports, however if I HAD to pick one sport to watch, it would be probably be Unreal Tournament, but since that's not real, hockey.
Heh, big football fan here. It's the best sport to watch, and the World Cup probably has as many viewers as the Olympics.
Sports like American football and basketball are fine to watch, but there's just nothing that keeps you at the edge of your seat. They'll do better, you'll cheer them on, it provides a constant flow of entertainment.
Association football keeps you bored while they're knocking the ball around, but when someone's in the final third of the pitch, you just sit there and stare, clenching your fists at the hope of a goal. And if they do score, you get to shout or tell everyone on the Internet that they did and everyone supporting your side gets as excited as you. You get a great moment, and you can tell everyone on the Internet that "my team beat your team" and they'll either go "**** you", or "woo, yeah!"
Association football just has a lot of passion in it. I've seen people give out discounts or boycotts over football results. I've seen people talk for hours about a single 3 min incident. You don't get that from any other sports. It may be a sport with cheaters and divers and a lot of boredom, but it's the best sport to watch with friends because of its unpredictability and the sheer pleasure of a comeback. Heh, kinda why my competitive game designs like to follow that "10% chance of scoring, 90% of nothing happening" model.
Disclaimer: Any sarcasm in my posts will not be mentioned as that would ruin the purpose. It is assumed that the reader is intelligent enough to tell the difference between what is sarcasm and what is not.