The decade channels were better when run by XM. Sirius has ruined them.
The whole service was better when run by XM. XM had, imho, more people dedicated to the idea of good and interesting radio. Low-numbers channels like Fine Tuning and Beyond Jazz were wonderfully diverse examples of "good radio" that Sirius killed off to squeeze in a few more segmented rock channels.
XM did a better job of jukeboxing the channels that fit that style (like top tracks) and putting live voices on the ones that benefitted from it (60's/70's and XMU for example).
They also had better music programmers. The aforementioned XMU, Fred and the like are just jokes now, playing mainstream music passed off as 'alternative'.