"Reality" shows are kind of becoming not-so-reality shows if you ask me. Take for example my wife and I visited the pawn shop where they film "Pawn Stars" in Vegas this past May when we visited there, and they did three "takes" walking in front of the building.
It was staged.
Not really reality when you have to yell, "Action!"
So, to answer your question, I'd have to say that there are NO best reality shows on television, considering the word no longer truly applies. Perhaps they should be called "reality style" shows instead or "reality satire"?
This becomes more apparent when you have "reality stars" who go from show to show.