Hockey. Hockey. Hockey. xD
Not just because I love the sport, but I find it fun to root for a team and talk with other people about it. Sports talk has even been the basis for many of my friendships, and it's always a great conversation starter, too. Obviously I can't control who's on my team and whatnot, but it's really cool to watch a sport you like consisting of the some of the best players in the world.
To me, anyways.