There are such a massive variety of JRPGs available on Steam that it's hard to know what to recommend without knowing what you have and haven't played, and which ones you've liked.
I played through Vengeance recently as my first SMT game, and enjoyed my time with it. Very fun turn-based combat with a lot of variety and a cool Pokemon-like "gotta catch em all" feeling to it. Extremely deep mechanics.
Visions of Mana looks great (I'm putting together the OT today). I've been a fan of the series since the Final Fantasy Adventures days - but it's got action RPG combat and an extremely polar vibe from Vengeance.
A few other recs I'd throw out that haven't been mentioned yet: