DDR Max. There were roughly 30 more songs, plus Oni mode. And if anybody whines about Bye Bye Baby Balloon, Ghosts, or So Deep, I'll fucking kill you. Hopefully Max 2 will continue the trend.

And Animal Crossing got some slight improvements. It's compatible with the e-reader. I'm not sure if the Japanese version lets you play the NES games on your GBA, but the US version sure does.