Like You see the First Grandia is a MUST PLAY... and I Think that Grandia II on PS2 too..
The 2 valkyrie Profile are MUST too, epecially the first one...
My selection would be like this:
PSX: Grandia, Lunar (both games), Star Ocean, Breath of Fire IV, Legend of Dragoon, FF Tactics.
PS2: Xenosaga (is a trilogy), Persona 3 and 4, Atelier Iris serie,Suikoden V, Star Ocean III, both Ar Tonelico, Rogue Galaxy, Unlimited SAGA, and if isn't problem a western RPG Baldur's Gate Dark Alliance, two games...