VS Sirius Stiletto SL100 Portable Satellite Radio Receiver   Samsung YX-M1Z Helix XM2go Portable Satellite Radio with MP3 Player There has been much debate over which satellite radio provider is better, Sirius or XM. These two companies have been compared based on a number of dimensions, including available programming, stock performance, the "Howard" factor, number of subscribers, etc. Now the two ...