I normally find turn-based combat really boring but I find Shin Megami Tensei games so engrossing in part due to the combat. You need to pay attention to mechanics and properly prepare for each boss fight if you want to overcome them. It’s not about just gathering enough exp. Do you know any games similar to SMT when it comes to gameplay?
I’ve played Persona 4 and 5 and am really looking forward to P3 Reloaded but it’s not quite the same enjoyment I found in those games as in the mainline SMT games. Party composition is not as much of a thing in Persona. I’ve seen Etrian Odyssey mentioned a few times before in the Megaten fandom so it seems like something I’d be into. The mainline games I’ve played are Nocturne, SMTIV and SMTV. I’m definitely playing Strange Journey next and then maybe Digital Devil Saga.
Since you’ve played P4, Persona Q might be a good on-ramp into Etrian Odyssey. It’s essentially EO’s gameplay with personas, characters and skills/spells from P3 and P4. Q2 has the P5 characters as well but only the Japanese voices (which is why I never got around to it).
Nocturne is my jam. I loved a review that called it something of a isolating, lonely and claustrophobic feeling of a game. And indeed when you are walking around the curved corridors of the kalpas, you feel like you are indeed deep deep below the earth.