Definitely the best video game music is from Metal Gear Rising: Revengeance. Stains of Time is my favorite.

Mortal kombaaaaaaat

Pa pa pa tum tum tum pa pa pa

Interstate 76

Beyond Good and Evil

Right now I'm going to have to go with a tie between Brok and Graff from Brok the Investigator and the legacy soundtrack piece After The Flames by Josh Woodward from SuperTuxKart.

Some great ones:

Gyruss (arcade)

Bubble Bobble (arcade)

WipeOut 2097(XL) (psx - probably the best example of songs that compliment the gameplay)

Afterburner II (arcade - just one specific track called City 202, at time 15:34)

Edit: 2 more

720 ( arcade - blistering)

Rolling Thunder ( arcade - max funky )

Final fantasy 6 Chrono trigger Street fighter 2 Street fighter v Super Mario Bros 3 Mega Man 2 Undertale And this is really unfair but Def Jam fight for New York

Okami has a truly beautiful soundtrack, my favourites are the 'The Sun Rises' and The Eight Dog Warriors Theme'. Also Calamari Inkantation from Splatoon is fantastic.

Halo is my top pick.

Goldrunner was also fantastic in its way.

For me personally some of my favorites (most memorable) are:

Hitman 2: Silent Assassin main title (and first half of the OST)

Divinity Original Sin 2 main title

Original vanilla WoW main title music

Sanctuary from Borderland 3’s OST

BFG Division from DOOM

Pretty much the entire Skyrim soundtrack

Most of the Witcher 3 soundtrack. My favorite is probably On the Champs-Désolés, which is from the Blood and Wine expansion.

SNES Wild Guns final theme Song

I am personally in love with Far Cry 5's soundtrack.

Just one track? The Requiem of Shield Knight from Shovel Knight.

Ys

Space Invaders

The theme song of Locoroco. Though the lyrics are in a made-up language, I can feel the desire for world peace in this song.

Tunic has an otherworldly soundtrack. It's perfect music to listen to while working. https://youtu.be/nnvjKf_mRYM

Mega Man 3 on guitar is fantastic: https://youtu.be/9__sJWMXjE0

I listen to "Carmeaty Burana" from Super Meat Boy all the time.

https://youtu.be/CRiyU6JZ3LE

Pretty much any Danny Baranowsky is gonna be good.

Deep Stone Lullaby fro the Deep Stone Crypt raid in Destiny 2.

It’s an absolutely beautiful piece of music, but so much impactful more when tied to where it appears in the raid as you battle your way across the underside of the space station, all of the other sounds muffled by the vacuum of space.

I don’t know who the guy is, but this video of DrLupo playing it with an orchestra playing the track live while he does is pretty damned amazing.

https://m.youtube.com/watch?v=33ZP8_aAdNI

Kenshi has some of the best ambient music. Scorching wind gives chills every time.

A few i havent seen mentioned.

Sonic 2 and 3 on megadrive. Especially the ice zone with the snowboard on 3. https://youtu.be/hYxlqTpZ-24

Icewind dale. The kuldahar music is epic. https://youtu.be/B92P1-OUNJo or easthaven in peace https://youtu.be/ERd5stTsaBc

There is a reason Touhou has two fandoms, one for its games and the other for its music. The music alone saved it from being another Oregon Trail and eventually got it its own anime.

Really really obscure but I could never take this song off my head, from A Thousand Arms, psx game. Game was a goor jrpg.

Underwater theme from donkey Kong country

It’s not better than Tetris I’ll admit. But I’ve always had a soft spot for the Mass Effect soundtrack.

Ace Combat

Skyrim was pretty epic… even the “wandering around” music was perfect.

But my #1 is Still Alive (closing theme song to Portal).

Not sure about best but the music the black mesa game did for the half life remaster was amazing.

Not exactly answering the question, but hearing every generational rendition of Proof of a Hero throughout the Monster Hunter games still gives me the feels

For me definitively the soundtrack of Boneworks (which is also the best VR game I know). Especially its main theme ("Bone Theme") and "Who am I"

Some more awesome OSTs in no particular order: Minecraft, Banjo-Kazooie / Banjo Tooie, Witcher 3, Risk of Rain 2

Wingspan. I have the Vinyl OST.

Monument Valley is quite nice too.