Kirby Superstar for SNES. Best in the Kirby series.
Recently, Zelda: Phantom Hourglass has grabbed my attention. It's quite nice.
Despite the touchscreen only controls (which work quite well for me, I might add) it's a must-buy if you have a DS. I'm at a lousy part right now though and have been pretty busy with my real life, so we will see what happens next and if I still like it.