I think Howard Stern is going to be the downfall of Sirius, but thats just my opinion. They are pretty much putting their company in his hands. They are risking ALOT signing has-been Stern for the absurd $500 million contract.
XM seems like a better company. Better technology, better hardware. 2.5+ million subscribers vs Sirius's 700,000 subscribers. XM stock trades about $32/share vs $3.80 for Sirius. XM is cheaper per month too!
I have XM, which I got because I heard O&A were coming (which I agree 100% judoGTI, they alone are worth it!!) but I really like the programming, I cant recall hearing commercials on the music station. You do on comedy, that I know, but its only for a minute or so out of say an hour of programming.
XM just signed with Major League Baseball, a $650 million deal. Makes more sense to sign baseball than NFL (Sirius)
Im sure you'd be happy with either one!