The day I was entrusted with the job of Admin on the server was a high point, certainly.
A corresponding low point was coming to the realization that RL matters made it impossible for me to continue in the Admin role just a few short months later.
Every piece of role-play as Synth-Foods-Convoy|104 was fun. There were of course ugly moments of uber 5miloryoudie goons, but for every 5 of those there was an encounter that made the countless hours of running food rations, synth paste, consumer goods, etc worth every minute.
An example off the top of my head:
Xenos forcing me to broadcast my support of the Xeno cause system wide in New York or face the consequences.