Fun question. I'm latching on to the term greatest here, which for me would be different than my 3 favorite cable game shows, which might include Idiot Savants and Lingo.
1. WBSM. This wasn't the first comedy game show, but the one who best included lots of humor without sacrificing content. One of the harder quizzers on cable.
2. Double Dare. Kids shows today still use elements of DD, which combined slime and substance into a show that was fun to watch by kids and parents.
3. Remote Control. Yes a predictable list, but this was another trailblazing show which paved the way for snark and a less serious tone on game shows.
Honorable mention: Smush. I think this is a format that could be brought back, perhaps to GSN.