The Persona games (ofc), unique modern Japan-setting mixed with Jung-inspired-psychological-cosmic-elements, addicting monster fusion system, fantastic soundtrack that compliments the youthful nature of the games' setting, usually making battles less tedious. Basically the shortest summary I could do for those.
Valkyria Chronicles, incredible tactical-strategy-turn-based-JRPG, neat characters that are rather likeable, good war story with a nice sense of progression told through a framing device, gameplay being incredibly fun, somewhat similar to that modern XCOM but more fun (at least for me) and all your troops have their unique talents & weaknesses making it actually feel tactical.
Digital Devil Saga, another spin-off of SMT with an incredibly dark post-apocalyptic story, plays quite similarly to Nocturne with some exceptions ofc -- like the ability to change equipped skills at will, instead of at level up. Unlike in Nocturne, unlearned skills are not lost forever, which allows for much greater character customization. The game features a 'Mantra'-system where Macca gained after battle can be used to download new Mantras at a saving terminal. Mantra is essentially a "set of abilities" which you can equip, they differ/vary between elements, physical attacks, or devouring (which is plot-related). Basically your main party are cursed at the beginning, and are transformed in horrible demons that need to devour other humans/demons in order to survive, that's the part where things get hectic. It'll also factor into combat, which is neat. Basically, like mentioned, it allows for a lot customization when heading out in battle..
Of course, the characters are very interesting, along with the story being very philosophically deep and thought provoking, though it spans into a sequel as well so there's a cliffhanger at the end. The largest negative about the game would be random encounters. A feature of the past that needs to be hurled into the sun at this point.