Always enjoyed Skyrim's soundtrack, but while I love it, I still enjoy and prefer Oblivions soundtrack more.
Oblivion was my introduction to the Elder Scrolls universe and the music from that game has kinda become embedded in my mind. Just my general go to music for fantasy environments including for DND or Pathfinder sessions.
I love Morrowinds music too, but if I had played Morrowind back when it first came out, I would have ranked it's soundtrack higher than Oblivions.