I like Balmung. Active in both US and EU timezones. Raiding if you want to get into that. Booming economy. FCs of all sorts. Player run events. The works.

Generally, to get in, I recommend very early morning (4-6 AM-ish) between Monday and Thursday. Do not trust the website list for what servers are open as it only updates every 4 hours (in game server list updates by the minute).