It took me a little while to figure out why AFL (I am aware the game is called 'Australian Rules' but that sounds hell of stupid) is my favourite sport, but I've concluded that it's because the game, more than any other (that I am curently aware of), is filled with opportunities for personal brilliance or amazing feats. Events like Maradona's Goal of the Century can occur on at least a semi-regular basis, and practically every game has a couple of moments of absolute brilliance. Even the worst teams (and as a Richmond supporter, you can trust me on this one) will provide moments of brilliance to keep you coming back. Whether it's a brilliant mark, a miracle goal, a sizzling run down the wing, or a midfielder exploding through traffic and leaving everbody in his dust, there will be something memorable about even the worst of games.
That's not to knock rugby though, I am a big fan of union. Not so much league, but I've been told that league is much better live than on TV, which is why it does comparitively poorly in the ratings, so I'll have to go to a live game some time.