my favourite rpg for the psp is Crisis Core, and for the Ds is "The World Ends with you".
Also i know i'm kinda a late entry for your thread, but from a die hard rpg lover to another, i say this good sir, thanks for bringing up this kind of threads, RPG's should be know throught out the world, it's the best kind of game there ever was, is, and it's going to be ;)
Current PC Build
CPU - i7 8700K 3.7 GHz (4.7 GHz turbo) 6 cores OC'd to 5.2 GHz with Watercooling (Hydro Series H110i) | MB - Gigabyte Z370 HD3P ATX | Gigabyte GTX 1080ti Gaming OC BLACK 11G (1657 MHz Boost Core / 11010 MHz Memory) | RAM - Corsair DIMM 32GB DDR4, 2400 MHz | PSU - Corsair CX650M (80+ Bronze) 650W | Audio - Asus Essence STX II 7.1 | Monitor - Samsung U28E590D 4K UHD, Freesync, 1 ms, 60 Hz, 28"
Essay Pro