I returned after being gone a year, and the OP is out of date. In case anyone else is wondering what the popular channels are:
LFT
Issue 23 is supposed to bring a new LFT channel. Until then, people seem to be using Help most often, followed by "Virtue LFG Beta" sometimes
TF/SF/etc
Mostly Virtue TFs, then Virtue Monsters, and Speed Trials. They often ask in help too
RP
look at the post above mine
Badges
Virtue Badges (not used much)
Generic Virtue Channels
Not sure if they are used much, but there are some people in: Virtue, VirtueUnited, and Virtue Forever United
