The West Team
The two servers where I have seen the most amount of event worlds/special events are .NL and .DK.However, staff do have the ability to organize events (and possibly open event worlds), and it's disappointing that they haven't used any tools at their disposal so far in that direction.
I played both servers ( and I still do on .DK), and one of the only reasons why they have a higher number of such events is because the players base is incredibly low.
NL, at this point, can possibly get 1000 (ish) players on their event world from all of their worlds combined, and more than half will lose interest half way through the event.
.DK has probably the smallest player base out of all servers ,with about 20-50 active players on each of the 3 active worlds.
What everyone seems to forget is that the majority of EN mods are volunteers who have real,busy lives, and they cannot dedicate hours upon hours (because that's how much it takes to create and run an event world) on a computer game on what is ,possibly, the largest server in terms of player numbers. Having players yell and point their fingers at you is more stressful than most think.