I voted for Press Your Luck. Even though it was done a few years ago, it needs to be done like it was on GSM (except for the slide problems like others stated). I thought the set would look dated by today's standards but I was shocked when it didn't. It looked awesome. It could look just like it did and I wouldn't have a thing to say about it.
Even though it was a nice touch at the time, we don't need Double Whammies and 3D Whammy animations. Crisper, redrawn versions of the old 2-D ones, with new 2-D ones thrown in would be great, but lose the 3-D schtick, it just didn't have the same sparkle when he took away the money. If they had to keep something from Whammy!, I'd have to go with the "Big Bank".
Match Game would be a close second for me, but I think it would be hard to assemble a good panel all of the time that would not turn it into MG98. When we watched the MG episode, my girlfriend, who isn't the biggest game show fan (but I've got her coming around) said "I'd watch it if it came back like this, I like Match Game".
As for Card Sharks, it would be nice if GSN could pick it up like it was on GSM (minus that odd bonus round), pair it up with another new version of a "Vegas-type game show" (Joker's Wild?) and place them in "Casino Night" as a weekly offering. Wishful thinking, but who knows these days?
I don't know, with the direction GSN is going these days (more towards game shows again) I looked at the GSM as a little window shopping for GSN execs as well. Maybe if they liked what they saw, they could contact Fremantle and say that they want to try one of those shows (minus Price and Feud, and maybe MG with the celeb factor).