I'd say a tie between Global Guts and Nick Arcade for first choice, and Double Dare after that, followed by Scardy Camp, and Wild and Crazy (the real wild and crazy). The rest of them I never knew well enough to really pick them. I wish I got GaS...
Global Guts always seemed awesome, because it was quite literally the kids Olympics, with medals and all. I always thought it was cool how they would play the national anthem of the winning country, and the aggro crag speaks for itself. What did the final medal count eventually end up to?
Nick Arcade is also a good one, just cuz I love playing video games. Sure they're old and out of date now, but then again the show is about 12 years old, they were top of the line then. If nick arcade was still around today... man alive, think of all the sponsors for nintendo, sony, and microsoft... As for the video zone, for some reason I always believed that they were actually in a river, or jungle, or whatever it was. Probably cuz I was 6 at the time.

Still would be awesome to try that just to see how hard it would actually be to do it.