Super Mario 64 DS - Still among the best platformer on any console. Stylus controls trump the D-pad, so go with that. It's very precise giving you pixel-perfect controls. The mini-games are worth the price alone.
Wario Ware Touched - This is quite possibly the best in the series. Although multiplayer support is very limited (there's a 2P ping-pong game) it holds the best collection of micro games. I feel it provides a much better experience than Twisted. Plus, like Mario 64 DS, I still play it regularly. The perfect take-anywhere game. Quick to turn on. Quick to play. Quick to enjoy.
Mario Kart DS - Arguably one of the best games from last year. Exceptionally tight controls, over-the-top levels and a good dose of single player essentials. Definitely will have you hooked until you uncovered every nook and cranny the game has to offer. Mission mode is like the icing on the cake. Or being able to play VS/Battle mode with CPU players.
Wario Ware Touched - This is quite possibly the best in the series. Although multiplayer support is very limited (there's a 2P ping-pong game) it holds the best collection of micro games. I feel it provides a much better experience than Twisted. Plus, like Mario 64 DS, I still play it regularly. The perfect take-anywhere game. Quick to turn on. Quick to play. Quick to enjoy.