You can run FFIV on a hacked PSP? I'm curious as to how you did that as it forced a firmware update on my system.

Pick up Etrian Odyssey or any of the Dragon Quest games for DS. Any Fire Emblem game that isn't Shadow Dragon would be a good choice too. Just be prepared to do a bit of grinding here and there. There's a pretty decent port of Tales of Phantasia for GBA too for another solid choice. Star Ocean 2 and Valkyrie Profile for PSP.