Bungie-era Halo has the best OST in the industry hands down, though recently Lunacid let me hear some certified bangers; someone here mentioned B:G&E, and I second that opinion although I wouldn't have thought of it myself.
I love EDM, so any game that uses it or is inspired by it holds a special place in my heart, like Streets of Rage, Rez, Dance Dance Revolution, or the Trails of Cold Steel games (especially the second one).
A lot of great choices already: Persona 5, Hades, Katamari Damacy.
A kind of odd left-field one I'd like to add specifically for great music in-game, is Guacamelee 2. I don't know that it's the kind of music I'm likely to put on just to listen to randomly, but as far as in-game atmospheric music goes I think it's both tremendous and refreshingly unique amongst the landscape of video game music.
Golden Sun GBA soundtrack. Also there are some really nice remixes of the fan community. The game is from 2001 but can be played with Nintendo Switch online subscription. As well as the second game (they are basically one game).
Unreal Tournament 2004 is my favorite OST by number of tracks that I love. It has several absolute banger tracks, like Morpheus3, Hyperblast-Redux, Convoy, Atlantis and Level11. I often keep a number of those tracks on my playlists.
Although I don't like the game itself much (I suck at it), Cloudbuilt also has some awesome tracks, my personal favorite is Aurora. The guitar chords at the apex is just heavenly.
Rebel Galaxy has some very nice stuff to feel like a 'merican space cowboy, it's mostly licensed music as far as i can tell.
Assault Android Cactus usually gets your blood pumping hard, which is great because the game is a pretty fun twin-stick arena. The tracks Assault and Licorice are just 👨🍳😙👌
... Come to think of it, looking at my list, I'm a real sucker for sci-fi OSTs, huh. I do want to make honorable mentions to Mass Effect (mostly 2), Skyrim and Smash Bros. Ultimate
Hard pick because I listen to a game or series for a while, then another. Just today I went and listened to a lot of Sonic tracks, which I do once every few months.
I guess Atlus games (SMT, Persona, EO), Metal Gear Rising, Ace Attorney, TWEWY are in the lead off the top of my head, but after a month I might give a different answer. My relaxing music playlist is mostly the official classical arrangements of Etrian Odyssey 1+2, so let's go with that.
Outer Wilds (and Echoes of the Eye) technically qualifies with the community's rules, but I think the answer more in keeping with the spirit of things is Shadow of the Colossus. The Opened Way is the most "fighting a building-sized monster as a normal guy but still winning" piece of music I have heard
Morrowind and project wingman are peak. FFXIV is fantastic with a persistent leitmotif across each entire expansion. The final endwalker boss basically wrapped up YEARS worth of story and that fight music was a medly featuring every expansion's leitmotif and holy shit I can't get over how incredible it was. Also the pandaemonium raid music. And Alexander. Seriously you can rabbit hole for HOURS on FFXIV music.
I’ve started recognizing when a section of a game feels baller, but it’s 99% because of the soundtrack. They can have the most generic basis for an emotional scene, and then as long as the music nails the mood it could be just blocks on a screen.
Final Fantasy XIV has had awe-inspiring tracks for the finales of each expansion since Shadowbringers; pretty much starting at the final zone through the final dungeon and trial.
Ace Attorney always gets it with its confrontation tracks; it could just be two people arguing in a hallway and it turns the battle of words into the most epic thing.
I’ll also give a shout out to Ori and the Blind Forest / Will of the Wisps. For both of those, it’s not just a few banger tracks for the exciting moments; even the downtime tracks are so memorable.
Pokemon USUM. If there was a looped version of the tracks, I‘d probably listen to it every day lol, it just boosts my mood. Sadly, the soundtrack (that I have) has them at 1-2 minutes.
Nier Automata, Cyberpunk, System Shock 2, GTA Vice City, Doom 2016 (I cannot listen to Eternals soundtrack knowing how Mick Gordon got ripped off there)