I'm going to get one of these games, but i have no idea which one to get. Persona 4: No idea. Heard it was good. 3rd birthday: the same Final fantasy XIII-2: Played the demo and it was decently fun. I liked the first one pretty well
Persona 4, I really enjoyed it. I highly recommend it! Need to be patient and smart, good luck if you're going to buying it. Very fun to play too; but I just heard those other games are good, though I didn't play them yet.
I'd say both Persona 4 and FFXIII-2 but... since I can only vote for one... Persona 4, for reasons I cannot be bothered to explain, but trust me... the Persona series is godly. 'Nuff said. (If you're unsure about P4 still... try watching the anime for a taster if you will. That could be a good idea)
With XIII-2, I didn't really find the story all that fascinating, but if You're more into game play, go for it. 3rd birthday is a fun shoot-em-up which is surprisingly rare for the PSP. I found it fun though. I would have to recommend Personna 4, mostly because I'm a hardcore RPG fan and the little twists that come along with the game made it great.