You have Xenoblade and Persona Q on your list already, so I'm going to assume you have at least a passing interest in RPGs.
The Etrian Odyssey games are what the engine in Persona Q is built off of. If you're enjoying PQ, you should probably give at least one of them a try. Between DS and 3DS, there are currently seven EO games, two of which (EO Untold: The Millennium Girl and EO Untold 2: The Fafnir Knight) are 3DS remakes of the first two, and one of which (Etrian Mystery Dungeon) is a Roguelike with procedurally generated dungeons. I'd personally suggest starting with EO3 (for DS), EO 4 (for 3DS), or EO Untold (a remake of the first game, for 3DS). A warning, though; EO games are on the tough side. You'll get used to it eventually, and the games tend to get easier as you play them, due to expanding options, but they can be pretty brutal at the start, although the 3DS versions tend to ease up a bit at the start, I've noticed. Playing the beginning of the original EO vs. the beginning of EO Untold is like night and day difficulty-wise. Getting ripped to shreds by butterflies is pretty brutal.
The majority of the games I own for 3DS are Shin Megami Tensei games, or related series. SMT 4, SMT 4 Apocalypse, Devil Summoner: Soul Hackers, Devil Survivor Overclocked, DS 2: Record Breaker, etc. Again, they're pretty tough, and the difficulty is largely front-loaded (although the DeSu games have better difficulty balance, IMO).
If you're a Dragon Ball fan, you might want to check out Dragon Ball Fusions. It's a pretty fun game. A bit on the grindy side, though; the game works kind of like Pokemon with Dragon Ball characters, including low "catch" rates on "legendaries", except attacks also have drop rates.
I'd also recommend the Shantae games, especially Risky's Revenge and Pirate's Curse.
