Q:
Best EU server for PvE to join?
A:
As above, you should only notice which server you are on with WvW not PvE. A map opens, if it fills a new map opens. If a large number of people arrive for an event or series of events and then leave multiple servers open and then close as the population goes back to what it was before the event(s).
Since megaservers, there’s no difference PvE-wise.
Yup, it doesn’t matter for PvE because of megaservers BUT come to Seafarer’s Rest, it’s one of the most populated servers AND we are good at WvW (in case you want fast leveling in EotM which is mostly PvE anyway).
If you do plan to invest heavily into WvW, your server is meaningless. All servers play together in PvE. If you think some PvE maps are empty, it is because there are just fewer players left in those maps even when combining ALL EU servers.