Paper Mario Sticker Star! Got it yesterday, my 4th 3DS game. It is adorable. I think the last Paper Mario game I played was Thousand Year Door, but I could be wrong. Totally digging it on a handheld. Feels more natural somehow.
And I still haven't popped in Zelda OoT 3DS, oops.
I have yet to play a game where I feel like I'm missing something with the 3D off, which is how my 3DS is 90% of the time. The Fire Emblem demo was pretty cool with 3D, but that's the only one where I really felt like it added something more interesting than the 2D version. SO looking forward to picking up that game in a little over a week!