i'd have to say the NFL or the NBA. sports makes the best reality show.
other than those i'd say the Apprentice.
i think the Playboy (or other XXX tv channel) should have a reality show. something like: Next Big Star, where 20 women are trying to work their way into Porn to become the next big star. you can have guest judges and one week can be stripteases, the next blow jobs, etc.
we should get moving on this immediately!!!