I want to make it clear that I love Daggerfall, Morrowind, and Oblivion. All three are fantastic games.
But Skyrim is the only one where I walk around outside just to listen to the music. To me, it just seems so....Nordic. It fits the atmosphere totally. Who ever did the music did not get paid enough.
It's definitely the best OST (out of Jeremy Soule ones). Oblivion's was OK (though not as good as Morrowind's) but Skyrim is the only one that I love to listen to outside of the game. And it uses some of the most memorable tracks from previous games - for instance my favorite one from Morrowind:) Ancient Stones is the best. (not to mention the ones with male choir;))