My preferred RPG on the PS3 is “Ni No Kuni Wrath of the White Witch”. It’s a masterpiece. The story is great. I own a PS4 for a few years now and it’s one of the few games that made me keep my PS3 (with Red Dead Redemption, still hoping for a remaster
Ni No Kuni: Wrath of the White Witch Review - IGN
A bonus, this game will never get outdated: the graphics are a pure beauty of animation. They are made by Studio Ghibli, one of the best (if not the best) japan anime studio. Studio Ghibli - Wikipedia The game music is also notable Music of Ni no Kuni - Wikipedia
I can’t find it anymore, maybe because I already bought the game, but there used to be a demo on the PS Store. So, if the demo is still available for you, you might be able to test the game before buying it. It’s currently 20$/20€ full price at the moment. It had been discounted at around 5$/7€ a few months ago.
Although the critics praised them a lot, I wouldn’t recommend Persona games. Not only because they are remastered of old PS2 games and so they don't exploit the PS3 hardware and graphics. But I have also played Persona 4 Golden (PS Vita remaster) till the end, and I still don’t understand why people enjoy it so much unless they like crawling in labyrinths for hours. For the story, it’s not a good RPG: very childish, targeted to teenagers. It’s very long, so you get bang for your bucks, but it’s also pretty boring. From a scenario standpoint, the old Final Fantasy games from the PS1 are better than Persona.