I'm serious too, I've listening to this in glorious FLAC format and it's amazing, not just the battle themes either but just the "ambient" environmental type music, I don't think I've ever heard a game ost that captures the essence of the setting perfectly. This soundtrack nails dark fantasy right down to a tee.

Disciples II has an awesome soundtrack but I love Chaos Gate's soundtrack more. :) Check it out.
http://www.youtube.com/watch?v=krdISG8U3Zk&list=PL48140F610132AC68

When I first heard these songs, I was shocked at how good they are. The soundtrack has a dark fantasy kind of sound even though it was made for the Warhammer 40K universe.

My pick goes to Icewind Dale :)
Best rpg soundtrack of all time.

Yes!!! I wish that I could completely forget about the game and replay it from the start. The vibe of that game sticks with you.

The first Age of Wonders also has awesome music, but less dark compared to Disciples 2.
https://www.youtube.com/watch?v=xE9UcirdTKQ

No Killer Instict 2013 has the best soundtrack in awhile:

http://www.youtube.com/watch?v=CVBpAikvnHk

http://www.youtube.com/watch?v=6Gpk3Qli-Cg

http://www.youtube.com/watch?v=ICKrtbT3PqE

http://www.youtube.com/watch?v=PUr48v3tyk0

Spinal's fucking theme sings in Swedish lyrics:

[Chant]

Kung och furste
Krigare
Kejsare
Härskare

Kropp av ben
Inget hjärta
Döpt i blod
Själlös, livlös

Ond Demon
Folkets hjälte
Hemlös Gud
Vilar här

[Sung]

Skogen den pratar, boskap på flykt
Fienden bränner våra marker
Rasslar med svärd och slår på sköldar
Redo att dräpa oss nu

Vi ber till dig spinal, lämna din kropp
Bli våran hövding, ta till vapen
Skänk oss din styrka vid denna strid
Vakna vakna, mäktiga Gud

Mörkret det faller över vårt land
Vindarna viner, marken skakar
Fienden samlas runt vårt rike, redo att kuva oss nu
Krigare samlas vid helig grav
Kallar på spinal, krigarguden
Hjälp vi behöver vid denna strid
Fräls oss, fräls oss mäktiga Gud

Flå! flå! flå!

Vi äter upp svampar för kraft och ?
Plockar fram yxor, brynjor, hjälmar
Med Guden Spinals krafter och mod
Seger, seger, segern är vår

Riket det skriker efter vår hjälp
Spinal han vaknar, lämnar graven
Med kraftigt tjut han samlar trupper
Redo att slåss för oss nu

SPI-NAL! RISE! LICH! KING!
SPINAL! SPINAL! SPINAL! SPI-NAL!

Yeah, it's good. Along with absolutely fantastic graphics style.

Disciples 2 OST is not too shabby (btw, have you heard the first game's OST? It's different, but charming, in a way), but I wouldn't call it the best there is.
I like Gothic 2 OST more. And there's also , [url=http://www.youtube.com/watch?v=naPhZbhDxMQ]Prince [url=http://www.youtube.com/watch?v=R7tDh6nkfVw]Persia, the Witcher... to cut a long story short, there are a lot of wonderful game soundtracks out there, with different "feels" about them.