There have been two products that instantly upon my first usage that I would endorse without any compensation, Plain M & M's and Bullfrog Sunblock. Now I have a third product to add to that list, my new portable Pioneer Inno XM Radio.
My main motivation is that I'm sick of terrestrial radio's music stations with comercials, and I wanted a more variety of talk options. For those reasons, Sirius you could argue is the slightly better choice, but XM has MLB, NHL and Pac-10 coverage, the top three sporting networks I could have asked for.
While the service has been great, the player I have is the topper. On top of it being a radio, it also works as an MP3 player. The best option is that if you've just switched channels and hit a song you like halfway in, you could hit the record button and it will save the whole song onto your device. I also like that you can easily set up prerecordings of certain shows and it will notify you when your favorite artists are playing on another channel.
To be fair, the negatives is that I don't get total reception, but mostly when I go through the canyons. They have a headset that also works as an antenna, so I'll give that a go soon. Also, setting the hookup into the car takes a little work, but I haven't put more than two minutes into it, so it's unfair to say.
So if Christmas comes early for you this year, get the Pioneer Inno.