I almost went XM but waited for SIRIUS because at the time XM had commercials, which I certainly wasn't going to pay for. Also, SIRIUS has NPR and PRI programming which is important to me. The coverage from SIRIUS is a little better as they have 3 satellites versus XM's 2. But now that XM has followed SIRIUS's lead and gone commercial free on the music streams, and also raised their price to the same as SIRIUS (now including features they once charged extra for, matching the SIRIUS offerings) it's really more about taste. They both have almost identical music line-ups, so it boils down to the entertainment channels. Think of it more as a Coke or Pepsi choice.

Check out both of their web sites and compare the content. If you're a sports nut or Howard Stern fan, you'll likely lean toward SIRIUS. Especially if you need your weekly fix of Car Talk or Prairie Home Companion. For the baseball fans then XM is your broadcaster, or if Andy & Opie ring your shock-jock bell. Oh, NASCAR is moving from XM to SIRIUS next year too.

So, just look and listen to figure your favorite.