i usually join the CIA server for a good game with FDF Mod.
also very important is tacticalblunder where lots of forum members happen to hang around.
played only 1 bigger coop on zeus yet and it was fun too..
the biggest disappointment with all the cool servers is that most of the times 2 or all 3 run at the same time, because then making the decision which server to join is hard.
btw: sven, did you make ->this<- pic ? parvus asked for it..