I like "The Real World" on MTV. I also love Super Nanny (I think Jo Frost is absolutely charming).
I use to watch Amazing Race on prime time, but lately it conflicts with other shows I enjoy. GSN airs reruns of Amazing Race, so I usually watch it on there. My favorite Amazing Race was the one Reichen Lehmkuhl competed in (I forget which season it was). I thought Reichen was totally gorgeous. His lover Chip was cute too. Both of them are too hot for color tv.
Most Haunted (I guess it is a reality show) is another favorite of mine. It is British and it airs weekly (Friday) in the U.S. on the Travel Channel. They investigate haunted castles and buildings throughout Great Britain, and occasionally outside of Great Britain.
Wife Swap is pretty good too, even though it is totally ridiculous and unbelievable most of the time.