xm radio

im am trying to decide is i should go with xm or sirrus which do you think is better. also i have a pioneer head unit so i think i have to go with xm anyways im not sure if i can get sirrus for it even. im just looking for some input. oh and also does the antenna have to go on the outside of the car or can i just stick it in my back window?? please give me some input thanks!

I think most of the antennas can go on the inside. My feeling, from listening around, is that XM will win out over sirrus.