I have had both services and IMO Sirius is better because I mostly listen in a car or party situation, and Sirius plays more popular tracks.....for being in a car or at a party that is more pleasing, I also like Sirius more because of the DJ and music news, to me XM is more like Musac......sorta lifeless and they do dig alot deeper into music as far as unknown tracks, so if you like more variaty XM will work for you, but Sirius is more entertaining and plays more popular songs, as far as Audiophile quality it isnt gonna happen.....I much prefer the Music Choice channels on my TW cable for at home sound quality. So in short I think you should choose based on programming not quality, and I hope some info I gave helps.
