If I had to look at it objectively I would probably say that the DS had a larger library of great games overall, though not as many of them were necessarily games I was interested in. The 3DS has fit my personal tastes a lot more, and I've had a ton of fun with it. (It gets extra points for having a "real" 2D Zelda.)
Currently playing:
Bloodbath Paddy Wagon Ultra 9