i was originally gonna write a long post about why this is my favourite console despite (and because of) its foibles, but instead i'm just gonna be standard here and say: good damn console.
neat gimmicky experiments and solid games mixing and mingling together to form a weird era of game design that carried over the spirit of the GBA by combining 4th-7th gen game design aspects into a melange that can only be described as "nintendo ds :)"
mine is Dragon Quest Heroes: Rocketslime
Mine has to be Big Bang Mini, a weird SHMUP where you shot by swiping the touchscreen in the direction you wanted to shoot and also moved your ship separately, with it just serving the function of a hitbox. Since you couldn't shoot and move at the same time, this is a game that could only really work on a non-multitouch touchscreen
rhythm game basic bitch coming in with Rhythm Heaven and EBA
(honorable mention to Lego Rock Band for the Amplitude/Frequency-like gameplay, and bonus points to Guitar Hero World Tour for the cool peripheral, but minus points cause it was uncomfortable)
TWEWY was great but only at cons, for me. The one that truly feels like a forever game for me is Castlevania: Dawn of Sorrow, on the original DS and DS Lite with the GBA slot for Castlevania: Aria of Sorrow, because it got you extra gubbins, and also it was just cool that you could do that.