It might be Rock Band. At least there's some sort of variety.
Mario's a good choice too because it's so expansive, and again, the variety. That's assuming the sports games (golf, tennis, kart) and the Mario Party games are included.
Mega Man is the classic sentimental pick for me, but I feel like they'd get stale, plus a big chunk of the classic/X series are sub-par.
I'd consider Halo if I had Xbox Live. That'd also be a big factor in Rock Band.
I just never got into Zelda games. I didn't really care for the style of game when it was on the NES, SNES, or Game Boy. The N64 games were cool, but I got rid of both my GameCube and Wii before the Zelda games for those systems came out.
Rock Band is a great choice. Honestly, if I thought about being stuck with one game series, it'd probably be a rhythm game or street fighter. At least with a game like that, there's no story and you could spend forever perfecting your technique. If I had to pick a story based series to be stuck with, It'd probably be Mass Effect since it's made to be played more than once.
I'd want it to be an expansive game. Not a game where there's a beginning, middle and end. That's what Zelda is. Arguably the best series ever made, and my personal favorite, but if I was stuck on an island and that was all I'd have to play, it'd get old eventually because it'd bet the same redundant shit time and time again. A game like Mass Effect or KOTOR is what I'd choose because there's so much to do, so many sub-plots within the grand scheme of things, that you can play it over and over again and still find more to do. So, I'd roll with Mass Effect or KOTOR.