Sirius updating channels
If you want a radio for driving around town, XM is the better choice.
But make sure that your area has a ground station if you have a lot of freeway bridges and taller buildings. It could be that XM is more mature, that the XM radios are better, or XM has better technology for sound. The main fault of XM is that the music is highly compressed.
XM has stopped doing much of this based on consumer complaints.
The commercials on XM are generally well done, and usually not very obnoxious.
XM used to have a tendency to run a commercial for an unrelated music channel on the channel that you were listening to.
I have had both a Sirius and an XM Radio since they each went live here in Minnesota.
While I did get my radios and first year of service for free due to being a Best Buy employee (at that time), I would have bought a satellite radio due to the long road trips that I take, and the lack of decent radio in many areas of the US.
At this time, XM now has the edge in being commercial free on the music side.