I do agree that the types of games that you're into factor into the choice between the 3DS or Vita. Persona 4 Golden is godly. Gravity Rush & Zero Escape 2: Virtues Last Reward are very good. Tearaway is great, Uncharted: Golden Abyss is pretty good, and Dragon's Crown is quite fun!
It's funny. Everyone here by far is mostly pro-Vita, while on Facebook, it's mostly pro-3DS. At this rate I'm gonna need another week. There's just too much good stuff out now and in the future that's making this a tough decision. Bravely Default, Ys Celestia, Pokemon, P4G, Smash 4 3DS... I feel like my head's gonna explode.
Seems like you're into JRPGs, more reason to get a Vita. A lot of promising titles in that genre coming to the system, including Tales of Hearts R, Mind Zero, Drakengard 3, list goes on...
Also P4G is one of those games where you'll lose countless hours of your life in XD