My first instinct was going to be PYL as well, but I think I would have to go with 70s/80s TPIR. The days of Johnny Olsen, Bob Barker at his prime, those pricing games that have long since left us, Janice and Holly...honestly, this was what I thought was the biggest treat when I first got to see GSN in the late '90s.
Even today, it still feels weird to have a Game Show Network without TPIR on it in any shape or form.
\same goes for J! and WOF, but I digress...
Anthony