But all of that is secondary because if you're going to pay for radio, it had better give you a pretty good reason not to pop a CD in the player or switch to AM and FM. Since the value of both services really rests with their programming, we arranged for three of our veteran music critics - Billy Altman, Brett Milano, and Richard C. Walls - to live with both Sirius and XM receivers for a month. The mandate wasn't necessarily for them to declare which channels were their runaway favorites, but to discover which offered the most intriguing and promising programming. Given that all three writers have eclectic tastes, we knew they would sample widely and wisely. Here, as they used to say on Dragnet, are the results of that trial.