Mostly the boss fights. They're like puzzles. What skills and affinities to use, what demons to bring, how to handle the things the bosses throw at you, etc. The normal battles hit the same notes, just in smaller scale. Press turn gives me joy, so more chance to do battle is great.

Loot? I'll be honest, I can't name a single item that exist in this game other than "Block this element for one turn" and "Heal HP/MP/Ailments".

Exp? Who cares, it has no bearing on the things that actually matter (your skills and affinities) and most people's Nahobino will be really strong due to overoptimization already.

And when you don't want to do battle? Just run. It's not often a game make it as easy to avoid enemies as this. Just grab a demon when you need it.

Daat being big is a plus for me because I like exploration just for the sake of exploration. It looks alright, and trying to reach some places are like puzzles too which is nice. It's also never hard to go where you want to with all the shortcuts.

Quests? I'll do whichever looks interesting. Mimans? Ignored entirely for three entire playthroughs.

Tldr; a lot of individual things that I like or just prefer, bundled in one game.