Haugen seems to have nailed the late-Nineteenth-century "orientalism" sound very well. "The Sands of Forgetfulness" brought Borodin to mind; it doesn't sound like Borodin, but it caused me to think of him. "Conarch Village" was nice, too, in the same way; faster tempo, but similarly intoxicating melody.
"Combat Aquilonia" was part of the current "shouting choruses" genre, so I hated it out of hand and didn't really think about it.
I really didn't like "Ere the World Crumbles." The drums were supposed to sound resonant and foreboding, but the reverb on them just didn't work. They sounded flaccid and hollow. The part where it was mostly the drums was dull, and then the singer started singing really loudly all the sudden. Then it seemed to just end abruptly. It was only then that I realized that was supposed to be the climactic ending, but the drums had failed to build up to that climax. Is that for the opening cinematic of the game? The pictures might make it clearer what was happening, but without that to lean on, I didn't think it was successful.

You know, it's strange, but I don't remember either. I know I have heard this song in-game somewhere. My brother says it's the exploring music in Conall Valley, in Cimmeria. Thinking about it, yeah I do roughly remember the initial part being played during that level, but memory of the chorus is stil fuzzy to me
I agree I'm not a fan of the battle music, with the exception of Knut A Haugen - II - Cimmeria. For an OST though, having 8-9 memorable pieces is probably more worth it than having only 1-2 nice songs in a pop/rock soundtrack, which is what most OSTs and pop culture soundtracks seem to offer

Here's some of my favorites that haven't been mentioned, in no particular order:
Overlord
The Longest Journey
Warcraft 2
Space Quest 3
Betrayal at Krondor
Loderunner
Dark Messiah of Might and Magic
Quest for Glory 1
Morrowind
Oblivion
Two Worlds

Morrowind one is just too good.

One Must Fall 2097
Outlaws

I missed a couple others:
Elder Scrolls 1: Arena
Elder Scrolls 1: Arena (2nd part)
Elder Scrolls: Battlespire

For me it's Beyond Good & Evil. But MGS's ones are pretty good too.
Oh, and Braid <3

Outlaws, without a doubt. Ultima 9 and Warcraft 2. Everquest 2 also had an outstanding soundtrack.

Agreed to AitD soundtrack, I also have it. AMAZING MUSIC

Original Quake, because Nine Inch Nails.
Arcanum - memorable string quartet music.
Icewind Dale, or pretty much anything by Jeremy Soule (GuildWars comes to mind).
Thief 1/2/DS - great spooky ambient. Fantastic games too, so I'm biased.
Pretty much all LucasFilm/Arts game OST's had scores that stuck with you for good. Monkey Island, Full Throttle (heavy metal soundtrack by Gone Jackals), heck, Maniac Mansion. Still remember the tune spewing from the PC speaker.
Some tracks from EVE (the space mumorpugah) are awesome.
American McGee's Alice has the most mental OST you'll ever hear.

Ok there seems to be a disconnect so I just want to be clear if I'm on the same page here. Are we talking about our favourite soundtracks here or epic ones? Because that's not always one and the same as I see it.
As far as epic I think Creative Assembly always delivered with Total War series. Rome: Total War was just about as epic as they ever could get.
Now as far as favourite, there are quite a few. Braid, Fallout 1/2, Starcraft, World of Goo, just about any Final Fantasy game etc. etc. etc.

Only games with "epic" soundtracks that come to mind are Total Annihilation and Mechwarrior 2.

Plus 1 for mechwarrior 2. That one stayed in my car almost as long as I played the game. Speaking of, when are they going to release another one?
the fact that the soundtrack spans such a huge game and never gets old.... is epic.

I've always been partial to the soundtrack of Hitman: Codename 47.

Amen.