trust me and 99% of the people on this website, get zelda twilight princess, you wont regret it. As for other games, i heard warioware is fun, i heard ssx: blur was good too. hmmmm, excite truck is really fun too
Theres alot of variety in the games, what are you looking for primarily? Multiplayer? Ease of play? Graphics? It really depends what kind of game you're interested in.
If you're looking for something to play alone I'd highly recommend Zelda: Twilight Princess, especially if you're new to the zelda series, I suppose you're not looking at your avatar but yeah, definately a great game.