I used to like a few of them, but got bored with the same format over and over again. I also think that the judges make a good contribution to the show. For instance, I think American Idol improved with the help of Steven Tyler (despite how much I was pining for his daughter! lol).
I admit that I came to know singers like Joshua Ledet that made me go buy some of their songs from iTunes, like the cover of Sam Cooke's A Change Is Gonna Come.