Ive been a subscriber to XM radio for about a year now and im completely satisfied. When I was faced with the decesion to pick between the two i chose XM mostly because the sound quality is better, their equipment is more advanced, the company is on more solid ground (their stock closed yesterday at $33 a share, compared to Sirius at $6 a share), they have a much larger subscriber base, and all their channels have digital quality. One thing that is not known about Sirius is that they operate off of 1 satellite stationed over middle north america, XM uses 2, 1 over the east coast and another over the west, that allows for better coverage. thats just my oppinion.