I would advise those who enjoy PvE/Raiding to run to Aether.
Crystal is obviously the RP center with a few low pop servers.
They seem to balance the problem with normal dungeons
but raiding and static grouping may prove to be the biggest issues.

I'm not sure about Primal, I don't hear anything about any of those servers
minus Leviathan being pretty populated? But that was years ago.

We have a lot of time to decide though. So I do hope people find a way.
This is kind of a big deal.