If you want SQ you will be majorly disappointed with either. They are better than FM, but not by much, and are nowhere near CD quality. What you want is HD radio, but only a few manufacturers offer it,and fewer places have it (though Portland OR has 9 stations at last check in HD) Honestly, XM is okay, but I still listen to my ipod 90% of the time, not that it's all that fantastic for sq either, but better that xm/sirius. Both services have that same compressed, muddy lows and highs that fm has- not the quality I expected.