I get a lot of Sirius on my DiSH Network receiver, and liked what I heard. Then, I did a 3-day free online demo of XM and found them to be about the same, so I went with the cheaper one. The hardware for each is very similar, and the set-up cost appears to be about the same.
I am now able to enjoy the radio again, and it seems there is always at least something on, now. It's an additional $6 or so for additional subscriptions.
It's possible the rates have changed. When we looked into it, they were either the same or Sirius was cheaper. There may have been other factors, such as programming.
Either way, satellite radio is great, we love it.
Glad you made the plunge and are happy with it!