Imo Legend of Heroes: Trails in the Sky is the best one,
if you don't count PSX ports. Meaning no xenogears, Final Fatnasy 7-9, Jailbroken SNES games etc. 

Valkyria Chronicles is pretty good but worse, than the PS3 version.
Crisis Core
Birth By Sleep

These games are sort of enhance ports of other versions,
Ys games
Tactics Ogre
Final Fantasy Tactics: The War of Lions
Lunar
are all pretty good.

^ Thats a good list.

By psp jrpgs do you mean actual psp jrpgs or do you want to include psone classic jrpgs?

Crisis Core is very good but there are so many other Jrpg's you can choose from, it's nothing like the PS3 ;P.
And indeed making sure you can play Psx or Nes games makes your range infinite...

Lunar and YS are good JRPGs'

ZHP:Unlosing Ranger vs. Darkdeath Evilman
Ys Seven
Crisis Core
Jeanne D'Arc