I decided on the XM and bought the Delphi XM2GO. I did an online trial of the music on each service and I preferred XM. I really couldn't tell you why because they both have huge musical selections. So, I wouldn't say that XM is better than Sirius. It was just my preference. Try both out online before you buy to see which music selection feels good to you. As far as receivers, I wanted one that did everything and this is it. I haven't tried it in my car or as a portable, yet, but it sounds great playing through my sound system in my living room with the built-in FM transmitter.