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...
Both the Nier games have amazing soundtracks that I listen to frequently.
Kena: Bridge of Spirits is also great although I don't really listen to it on its own. It really makes the game feel much more impactful while playing.
Nier automata has a great soundtrack, i haven't played the newer one yet, but Drakengard 3 has some great songs on it, if you haven't played it its meant to come before nier world lore wise.
Also gotta give a shoutout to World of Warcraft, got some massive nostalgia from that soundtrack
I actually got Drakenguard 3 running on my steam deck recently, it runs surprisingly well. I could immediately tell the game was gonna have great music based on the opening animation.
I find Nier replicant is good only after you make it past the first one or two hours. Too many fetch quests for me.
I will say drakengard 3 was one of the grindiest games ive played haha, dont wanna spoil anything though so thats all ill say. But its worth it the story is good if you like yoko taros type of storytelling. Theres a 60 fps patch i used but idk if steam deck is good enough for that, my old pc could barely handle it at 60fps with an i5-6600k and rx480