I don't know what Sirius' lineup is like, but recently four XM music stations started running commercials. Not a good sign. Those stations have the letters "cm" after them so you can see that you are going to get commercials.
And XM Kids has a little bit of commercial content, but not much. I just recall hearing two Ball Park Franks commercials on that station in all the hours we have listened to it(which is annoying for me because we're vegetarians).
Sirius seems to have a stronger lineup now, music-wise. It looks like they have everything that XM has but a little bit more.
Comedy-wise, Sirius has an extra comedy station, that's called something like "Working Man's Comedy" - that in addition to their X rated and family comedy. XM just has a family comedy and an obscene comedy station.
I like satelite radio though. I like being able to see what artist and song is playing. If I just listened to music in my office I would use internet radio, but you cannot use internet radio in the car (as far as I know).
I have read that both these stations are bleeding millions and millions of dollars trying to get off the ground. I have read that it is a fight to the death, that probably only one station will survive and eat up the other one. Higher prices are inevitable as the cost of hiring stars like Oprah Winrie and Howard Stern is substantial.
Beakybird