Well there are quite a few since 2013
Mod: 501st, BTR, Volki, SVR, CLF, SDS, RSM, Dragonzu
All great fun to be apart of or to see in the server. Each being unique to the server and lets not get started on the fun of a roadblock.
SA: Convicts, Runners, GenZ
Its a tough one because I've been in a few groups during SA but personally nothing has come close to the memories I have of the mod. Why that is? I have no idea maybe its because of the buggy state of SA being in Alpha for a majority of the time played.