PSP RPGs: Which are the ones i should own?

[MRKs]

I heard good things about Legend of Heroes: Trails in the Sky, but I didn't played though.
Currently I am playing Persona 3 Portable and it's much better than it's console version, so if you love P4 you should play P3. It's waaaaaaaaaay better imo.

Also, maybe you can try God Eater Burst, I loved that game, put it around 60hrs it's a mix between monster hunter (don't worry I read your OP) and an action rpg, you can have a party and kill monsters. It's perfect to play on the go and it has local multiplayer plus a nice story :)