Same as what's already been said. I have Sirius in my car, but have had a large number of rental cars which typically give you XM. IMO XM has better jazz and blues stations, with deeper playlists than Sirius. XM also has deeper punk and alt playlists (again IMO). Sirius may have the edge on pure Rock 'n' Roll. Classical is a toss up so far. They both sound like cr@p compared to a high end system and source (I sometimes bring my radio into the house and hook it into my system).
