Too many to list ...

My current favorites:
Alec Holowka - Dusk Stars (Night in the Woods, the whole soundtrack's worth listening to)
Ed Hargrave and Adam Hay - Industrial 4 / Mission music (Seraph)

One of my all-time favorites:
Olivier Deriviere - Nilin the Memory Hunter (feat. Philharmonia Orchestra) (Remember Me)

Currently I've been listening to the Samorost 3 soundtrack (and supplemental Pre-Remixes EP) by Floex. All of his game soundtrack work - for Machinarium and the Samorost games - is exceptional. The Botanicula soundtrack by DVA is hilariously quirky and wonderful, too.

If you've never played those games they may not sound all that great. But if you have? Then you will certainly get the wistful and wondrous themes.

Soundblaster or Roland MT-32?

https://www.youtube.com/watch?v=cpYaZXHyp8g

https://www.youtube.com/watch?v=uvkuT8cy4cY

Oh, also this one:

Aakaash Rao, Brenden Frank, Selcuk Bor - Valley (feat. Zefora Alderman, Deryn Cullen and Lucian Nagy)
(from the eponymous game)

Works best when combined with the visuals though.

SoundBlaster.

My memories are purely from back in the day (92-93) U7 game/music just stuck after all these years.
The temptation to purchase Roland MT-32 nowadays is very strong. It’s such a cool looking bit of kit and the sound!

The sensible side of me is weighing up the cost and desirability for retro hardware when emulators, such as say, Munt cost nothing (so to speak).

I still want one!

My fav 1980s composers and arrangers:
http://minirevver.weebly.com/top-composers-1980s.html

I was going through female video game composers in an earlier post in this topic, but I didn't realize back than that the excellent Castlevania 1 soundtrack was composed by a woman (Kinuyo Yamashita). She also composed the original music for Mega Man: The Wily Wars.

There's other excellent music in the series, including Castlevanias 2, 3, 4, Bloodlines, Symphony of the Night, Portrait of Ruin, and others.

As for individual tracks, I could mention the track that plays in Wily Stage 6 in Mega Man 2; I believe the same tune appears on the title screen of Mega Man 1.

By two women, she did it with Satoe Terashima:
http://www.vgmpf.com/Wiki/index.php/Satoe_Terashima

One of the early 80s VGM pioneers was also a woman, ​Yuriko Keino.

She did Dig Dug (ARC), Pac-Land (ARC), Dragon Buster (ARC), Grobda (ARC), and Baraduke (ARC)
​​

The opening soundtrack to the PS1 wargames defcon 1. Not the PC version, could barely get that to work 15 years ago.

The menu music for fantasy general.

Tenchu 1 PS soundtrack. The ending music I really loved if a bit depressing.

One must fall 2097 menu music, my favourite.

I hate it when classic PC game music gets badmouthed due to rinky-dinky Adlib music. Take for example this:

https://www.youtube.com/watch?v=4bD8KxNYJj4#t=50

So the town music of King's Quest 5 is nominated as #10 for the worst video game music ever. However, the game was optimized for Roland MT-32, and with it you can hear it is supposed to be some kind of "market music" someone is playing in the town, and there are sound effects too that don't make sense in the Adlib version (hammering of wood, a dog barking, people talking (mumbling)).

Here is the Roland version of the same music:

https://www.youtube.com/watch?v=68clKOeaWp8#t=883

Yes yes, I know most people in the world never had a Roland sound card, but so what? Most people in the world don't have gaming PCs at all nor socks in their feet, how about that, huh?

After all, if we go that route, we could just as well list any PC beeper music as the worst video game music ever.

Some DOS games did have good music, despite suffering from the limitations of PC sound cards at the time. In particular:

Might and Magic 4: Clouds of Xeen
Might and Magic 5: Darkside of Xeen
(Note that these two games have very different soundtracks written by different composers despite the fact that they can be combined into one; World of Xeen uses both soundtracks depending on which side you are on.)

The Elder Scrolls: Arena
The Elder Scrolls 2: Daggerfall
(These two games share much of their soundtrack.)

Ultima 6: The False Prophet
(First Ultima for which the DOS version has music; Ultima 3-5 have nice music, but not in the DOS vesion (and the NES versions (but not Ultima 6 SNES) have completely different soundtracks.)

Unclear if you are referring to Adlib music, or what. Many, if not all, of those games supported also Roland MT-32 or General MIDI.

Mind you, there are some genuinely good Adlib music too, like 688 Attack Sub, Dune (I prefer the MT-32 music in that too, but the Adlib music is quite fine too), and also some Japanese RPG or strategy PC game I heard in a Youtube video but don't recall the name of it anymore (too bad because it had probably the best Adlib music I've ever heard).

688 Adlib: https://www.youtube.com/watch?v=IGtIQOTXszM
688 Tandy: https://www.youtube.com/watch?v=4_j_0nbff28 (I wasn't aware of this before, sounds nice too!)
Dune Adlib: https://www.youtube.com/watch?v=dRJIO6a5lDQ
Dune MT-32: https://www.youtube.com/watch?v=t9K2UxJTgGM

I am referring to whatever DOSBox defaults to, which I believe is AdLib (or at least something that sounds like it); that's the version I am most familiar with.

As a side note (related to my Ultima comment in the post you're replying to), Ultima 3-5 do have good music on platforms that have them.

The NES versions of Ultima 3 and 4 have decent music. I prefer the music in other versions, however.

The NES version of Ultima 5 managed to have one track that is decent. Unfortunately, that track only plays during the intro and ending; the rest of the game plays the same annoying 19.2 second track over and over and over again. (I do not recommend playing this version, unless you are intentionally looking for a bad game to play.)

The SNES version of Ultima 6, unlike the NES Ultimas, uses the same soundtrack as the DOS version, but remade for the SNES sound chip, and it actually sounds quite good.

DOSBox doesn't really default to anything, it supports both Adlib and MIDI music out of the box. However if you are talking about e.g. the GOG versions, they quite often are configured to use Adlib/Soundblaster music by default as it works for everyone the same (General MIDI music should also work, but MT-32 music would need either a real MT-32 compatible sound device, or a Munt emulator driver).

I recall though some GOG games have been set to either General MIDI or even MT-32 by default, not sure if e.g. Ultima Underworld or Betrayal at Krondor were such. As said, setting it to MT-32 by default doesn't make sense as it will sound wrong to most out of the box (unless they use MT-32 or Munt).