Hi Mitch...
In my system, FM reigns as champion. I have Sirius radio set up in my main system. It sounds good, but due to the Sirius receiver being pretty much a "mid-fi" component, it's sonic performance is hindered. I own a vintage Kenwood 600T FM tuner that delivers a better soundstage and a more musical presentation. The signal sounds less compressed and is less fatiging. Hopefully, XM and Sirius will upgrade their products in the very near future. I listen to both of these sources alot and enjoy them greatly as they both offer such a good variety of music.
Enjoy.....