Anathema is fine.
Elysium is way too over populated, not even debatable. Questing is premium cancer, but grouping for dungeons I would imagine would be either sublime or aids depending on who you group with, but at least you'll find a group almost immediately versus the 15-30min average wait to assemble a team for any low level dungeon on Anathema.
As for PvP it's hard to say, I've only been ganked once by a high level player (in hillsbrad ofc) and I'm level 31. Plenty of opportunities to be ganked in Ashen and Stonetalon, but 9 times out of 10 when i run into another player we just wave and keep moving. PvP feels like a waste of time because there's rarely anyone at your current quest/farming location. As for high lvl zones I imagine them being a lot more competitive but far less toxic than Elysium's.
There's always guilds spamming for new members, demand is high on everything right now except maybe warlocks and hunters from what I can tell.