I think Nintendo Land wins hands down because, so far, it is the only title that has given truly unique game experiences with the asynchronous multi-player games like Mario Chase, Metroid, Luigi's Ghost House, Zelda, etc. The person on the gamepad plays with everyone else but is doing something different. It is unique and fun as hell. Also, some of the games use the gamepad camera to put a real-time image of the gamepad holder's face on the T.V. and that is some unexpectedly hilarious **** for the other players.
Other notables are Sonic and All Star Racing Transformed where two folks can race without having to use split-screen and, similarly, Call Of Duty Black Ops 2, where two folks can do local or online multiplayer, again without having to use split-screen. This is excellent.
Zelda Windwaker also does a good job with inventory management.