Super Mario 3D Land, Star Fox 64 3D, The Legend of Zelda - Ocarina of Time 3D, Mario Kart 7, Tales of the Abyss, Resident Evil: Revelations, and Kid Icarus. These are the games I've enjoyed the most next to a few of the downloadable titles like Pushmo and Mighty Switch Force.
The Legend of Zelda: Ocarina of Time is a must!
Super Mario 3D Land is very fun and enjoyable although a little short.
Mario Kart 7 is awesome, another must!
These are the games that I have played that I recommend. Nintendogs + Cats is alright, but I would wait for a price drop if you want this game. Like most people already said, more games are coming out within the year that also should be awesome to get!
Also, if you are familiar with the Nintendo e-shop, the 3DS has one as well in which you can buy games (not sold in stores) and applications for usually $7.99 or less.
Animal Crossing 3DS, which is yet to be announce an official release date.
Mario 3D Land and Mariokart 7, if you like mario games.
Sonic Generations, if you like Sonic games.
If you like fighter games, IDK.... cause I don't normally buy those.
I say Legend of Zelda, Mario Kart 7, Super Mario land 3D and Kid Icarus. Fighting games i would recommend Dead or Alive Dimensions, That game is very good =]
Got my 3DS when they had that Trade an old Version in get money off Deal!
Here's what you traded and what you paid after the trade-in.
DS trade in - 179.99
DSi trade in- 159.99
DSi XL trade in - 139.99
I traded in my DS and alot of other stuff.
It ended up as 80 bucks when all my trade-ins were done.
Though I had most of that on gift cards and my power-up card.
I ended up paying 20 bucks cash!