I have been an XM sub for many many years. Ever since Sirius took over XM's service and quality quickly went down hill.
Most of the rock stations on XM were replaced by the much worst and more limited library Sirius stations. Even before the merger, the Sirius rock stations had a smaller library than the XM library. Now they both have an even smaller library
Signal reception has gotten much worse. I seldom to never lost a signal, even while driving through a forest or in a small tunnel. My dad, who was with Sirius for years, always had worse signal reception. XM always had several ground repeaters. Since the merger, they cut down on the number of ground repeaters.
On-line access with XM was ALWAYS free with an XM subscription, while Sirius on-line access had a small fee with the Sirius subscription. Once the merger happened, SiriusXM then required XM subs who were getting on-line access for fee, to pay an additional $3 to keep their on-line access. Some of us were able to keep getting the service for free with a life time subscription. Unfortunately, the on-line access is tied to the receiver, not the subscription. Once you change receivers you then lose the free on-line access.
In short, Sirius made XM worse by reducing the music library, cutting back on ground repeaters (worse reception), and requiring XM subs to pay extra for on-line access.
Why do I have XM? Mainly because of baseball