I've always loved Family Feud. It's a simple concept and Steve Harvey is absolutely hilarious as the host. I also love classics like The Price is Right and Wheel of Fortune.
Not sure if it counts as a game show, but Wipeout is great. It was one of my favourite TV shows when I was younger.
I don't know if this classifies in the same category as other game shows listed here because its a season long game, but Big Brother is one of my favorites. I really enjoy the strategy and social plays of the game.