Satellite radio - XM or Sirius?

[cognito20]

My wife and I are finally taking the plunge, and subscribing to satellite radio. What are the relative advantages and disadvantages of the two satellite services, XM and Sirius, and which one do you like better, and why? I know Stern is moving to Sirius in a month or so, and while I like him I like Opie and Anthony on XM even more, so Stern being on Sirius is not going to make me choose them unless they're also better in other ways. Please help us to make an informed decision here, because on the surface I don't see a lot of difference between the two services. Thanks.

--Scott