It really depends on what of kind games you want to play, if you're into the gimmick, Uncharted and Tearaway fully utilize all the feature the vita has.
JRPGs dominated the market as I said before, other than that you might want to do some searching, here are some of the games that I like personally, I will list them by genres so its easier for you to decide.
Hunting-games:
-Freedom Wars
-Toukiden Kiwami
-Soul Sacrifice Delta (Digital only for region 1 psn)
Action/Adventure:
-Uncharted
-Jak Collection
-Akiba's Trip
-Gravity Rush
-Guacamelee
-Little Big Planet
Shooter:
-Resistance Burning Skies
-COD Black Ops Declassified
-Sine Mora
-Borderlands 2 (PC is better, that goes without saying. Digital version takes more than 10 gigs, get the physical.)
RPG:
-Persona 4 Golden
-Disgaea series
-Demon Gaze
-Neptunia series (This one is hit or miss, the whole game is very heavy on reference of video game industry and history, movies, animes, shows, and pop culture icons in general.)
-Final Fantasy X and X-2
-Ar nosurge Plus (The physical version is limited, almost sold out on the 1st week alone and now might be rare as hell, so yeah, digital.)
-Ys Memory of Celceta
Fighting:
-Marvel vs Capcom 3
-Blaz Blue
-Street Fighter x Tekken
Puzzle:
-Virtue Last Reward (Best if you play the prequel first on DS, 9 doors 9 hours 9 person, get ready for mind fucks)
-Danganronpa
That's all I got in mind for now, my personal favorite would be Virtue Last Reward and Soul Sacrifice, the latter convinced me to buy a vita.