What is your favorite game OST ?

Outlaws

https://www.youtube.com/watch?v=80u82h35neg&list=PLqcGvP7TBm_muGvK8jqjL4Jceo6kCptsF

I've spent a lot of time listening to these:

Freedom Planet
Mother 3
Paper Mario
Pokemon Mystery Dungeon: Explorers of Sky

With an honorable mention to Skies of Arcadia, Trails in the Sky, Super Mario Galaxy, Professor Layton... there's a lot of great music out there!

Ori and the Blind Forest
Hollow Knight
Chains of Satinav
Glass Masquerade
Bastion

Machinarium
Samorost 3
Botanicula
Chuchel

Advent Rising https://www.youtube.com/watch?v=G89Li5-pFRU&list=PL0546B6407E681E0F&index=3
Need for Speed: Porsche https://www.youtube.com/watch?v=Zg7X8e_WwoI&t=874s
Crysis 2 https://www.youtube.com/watch?v=Iy4iQvJo24U (I remember when the game was BETA, I would launch the game just to listen to the main theme)

Frostpunk
https://youtu.be/WtzOHYi3CIk

The Last of Us Part II - https://www.youtube.com/watch?v=X-swJqjzjCI

Gustavo Santaolalla is a genius, he remains to be one of the best parts of this series. Special shoutout for Part I as well.

• Metal Gear Solid - The Best Is Yet to Come
  https://www.youtube.com/watch?v=R0gxcY6tt3Q
  https://www.youtube.com/watch?v=yWGVRxJOKw8&t=143s)
• Portal - Still Alive
  https://www.youtube.com/watch?v=Y6ljFaKRTrI
• Skyrim - The Dragonborn Comes
  https://www.youtube.com/watch?v=BSLPH9d-jsI
  https://www.youtube.com/watch?v=hnXD6FRZtn0

I have a friend that wanted me to post these-
Streets of Rage - Keep the Groovin
Y's Seven Innocent Primeval Breaker
The entire OST from Super Fantasy Zone
Unreal Gold Nightvision
Unreal Gold All Hallows Sunset
Eye of the Beholder 3
Wild Arms 4 - Over the Wind
Wild Arms 3 - Battle Theme
Lunar Silver Star Story FULL ost
Lunar 2 Eternal Blue

Dropping an extra from me- Ravenloft: Stone Prophet - Song of the Elusive Ghost.

i don't have rankings but Gabriel Knight: The Beast Within ost (in game music) was great and memorable for example
edit: https://www.youtube.com/watch?v=_wGjD19IB-0

Some of mine:
Fract OSC
The Binding of Isaac: Antibirth
Slay the Spire

The Binding of Isaac OST

TES V: Skyrim. Can't get tired of It.
Just to add something I listen not long ago while watching a stream and I think It's worth It
Tail Concerto (1998) https://youtu.be/SIgvuBDHvLs
Cheesy characters aside the sound is amazing, It sucks that the tracks are a bit short.

Descent
Final Fantasy Tactics
Beyond the Beyond
Super Mario RPG
Shadowrun (SNES)
Doom (original)
Final Fantasy 6

Tom Clancy's Splinter Cell Chaos Theory
After playing this game I became fan of Amon Tobin (aka Cujo, aka Two Fingers)

These are some of my favorites.

DOOM 2016 OST

Highlights:
Rip & Tear
Flesh & Metal
BFG Division

DOOM Eternal OST

Highlights:
DOOM Eternal
The Only Thing They Fear Is You
BFG 10k
BFG Division 2020

Resident Evil Classic OST

Resident Evil 2 Classic OST

Resident Evil 3 Classic OST

Eadily The Witcher 3, best music created for any medium

Ori and the Blind Forest is the top contender for sure.

Other than that...
Trine 2
Robot Roller-Derby Disco Dodgeball
Assassin's Creed II
Payday: The Heist menu theme is cool, and Payday 2 also has some really good heist tracks (and made me discover a new artist I like, LeCastleVania).
Cave Story (Catchy tune...)

The dungeon/boss soundtracks from Closers hold a special place in my heart because it so fucking pumping. Unfortunately there is no credit and very few sources where you may listen to the soundtracks, but I realized you could get them directly from the game folders so I did that and had them published on khinsider for posterity.
This one is a particular favourite among many.

Ez, Good Time Garden https://www.youtube.com/watch?v=wDtvACvCK9w

Red Alert!
https://www.youtube.com/watch?v=HvH5WXovz0c

My TOP9

Beyond Earth

I've seen Life is Strange mentioned already but it just has to be, there is no other game that comes close. I love the music in LiS so much
https://www.youtube.com/watch?v=LnG6icGIm0o&list=PLT1zim-_E9NEHF7GfkgInhE_glOTcK9S-

Bastion

GTA VC
GTA SA
Hotline Miami
NO THING
LOVE