I have both, I prefer XM, because I never lose my signal on my boombox, but I can't say the same for Sirius, it constantly goes out. I'm sure I'm not the only one with that problem. I love the NFL network on Sirius but that's about it. I think the music channels are a wash. XM has O&A, Ron and Fez, and MLB. I travel all over TX, OK, so this time of year, I won't miss a single Astro game when I'm on the road. And also, like somebody mentioned earlier, XM already has a recordable portable unit, and they have their second edition portable coming out this month, and it's the size of a cell phone. XM is far superior in technology, and it seems Sirius is the one in financial trouble and overpays ( Howard Stern ) for talent.
Ive got XM. I only listen to channels 80-82 which includes BPM. I can honestly say that this channel rocks. I was told they are adding more trance/dance channels as well.
Many smart people on Wall Street believe that XM will be the longer term survivor of the satellite radio battle.
Sirius has the NBA and NFL and College, I cant stand baseball. so thats why I got it. I've had no major reception problems. I get the Kenny Smith show (Full Court Press)!