PSP has Luso, which is Ramza with an innate "poach" with his squire class. Everything else aside, this makes the PSP version better end of discussion. You also get Balthier, which is pretty cool though I dont care to use him, and theres several extra things to do like the Beowulf/Reis extra stuff that was mentioned (you can steal SUPER ULTRA MEGA FAT loots from this).

*I also decided to try Reis on my current file only to find out she has the best stat growth in the game so now I am amazed (take that Orlandeau!).