Personally, I'm a huge fan of Hollow Knight, Ori and the (Blind Forest/Will of the Wisps), and Kingdom Hearts. Orchestral soundtracks are just something else...
Every Korean anime online game i've ever played has had an unnecessarily good soundtrack. Maplestory, Mabinogi, LaTale, S4League, GunZ: The duel, the list literally never ends.
Man, this list gave me a rush of nostalgia. I played all of these (except Mabinogi and LaTale) growing up, and their soundtracks are still deep inside me, especially Maple Story.