My friend Tegan made me think about it. I don't have a clear list yet, but (in no particular order) it would include the below songs:
Steel for Humans - Witcher 3
Hades Theme - FF14
Down by the River - BG3
Lakshmi's Theme - FF14
Wind Waker Theme - Wind Waker
Rescue Girl - Mighty Switch Force 2
probably too much of the WoW soundtrack to name
The World We Knew - Sayonara Wild Hearts
Welcome to Los Santos - GTAV
I also don't have a definitive top 10 list, but these would probably be on it:
Ashes to Ashes to Ashes (to Ashes) - Deadbolt
The most chill and melancholic final boss music I've ever heard in a video game. It took me many, many deaths to actually beat them for the first time, but this track helped me take a deep breath and try again.
Tallon Overworld Depths - Metroid Prime
Most of the soundtrack in this game is excellent, but this is the one I come back to the most. By far my favorite ambient track in any game.
Fractured Shrines - Dead Cells
Once again, most of the Dead Cells soundtrack is great, but wow. The strings here go so hard in the song's climax that it always leaves me with chills. Also, go check out the Dead Cells: Return to Castlevania OST because it's almost flawless.
Snake Man Stage - Mega Man 3
There are so many damn good Mega Man tracks that it's hard to pick just one. I can't help but imagine snakes slithering to the beat every time I hear it.
Aetheres - Amid Evil
A surprisingly beautiful piano piece from Andrew Hulshult that matches the ornate and arcane world it's in perfectly. It's kinda mind-blowing that this came from a composer known for heavy metal tracks.
Shamburger - Age of Empires II
I will never get over how one instrument kinda sounds like a whale, but it's still an iconic track. This is one of those songs I put on if I need to get work done because it always gets me in the mood.