They had a two season run of a show called Jockeys on Animal Planet that I really enjoyed. I've actually watched the full series a couple of times. I don't know shit about horse racing, so this was educational and it was a well done show. And you can't script a horse race.
As Harley Spencer stated, it's entertainment. That written, I like Hoarders, Intervention, Jersey Shore, the Kardashians,Ice Road Truckers and their spin off, and Pawn Stars.
Since I'm a hacker, I also like The Big Break.
Coming from someone who generally HATES "reality" television, it is almost hard to admit I like anything in the genre. With that being said, I really enjoy Pawn Stars and Storage Wars.