We have Sirius and love it.
DH loves the commercial free music, and ability to program his favorite artist in so he get's alerts when they are played.
DS loves the kid's stations (Radio Disney)
We love getting reception on the road.
I love the "Sirius Left" talk station, a nice break from all the "right" talk on commercial radio.
We have the home kit (connected to our stereo) boom box (used outside and in the RV) and car kit, so we just simply move the receiver to where we want to listen to it.
I think Sirius is a tad bit more expensive than XM, but not by much, and they have specials. We paid in advance for 15 months at a discount, and got rebates on the hardware purchases when we bought.