All the above.
1) Having admin feels great because it really lets me feel like I'm helping keep the servers "punk-free". And I love being able to help others when they have problems in the servers.
2) The community of people in eGO are just plain awesome. I won't lie and say everyone is perect, as I'm sure everyone gets on each other's nerves sometimes. But I've made a ton of awesome friends to play with, chat with, and just have fun with.
3) The servers are some of the best ones out there in the PC games I play. I tried other servers before, and I just get annoyed with the attitude from people on them. eGO is more laid back, and a helluva lot more fun.