Dyegov is correct. None of the servers are as populous as they once were, but Artemis still has the highest population. I've not seen any of the other servers "Crowded" for quite some time now. Govinda and Reni seem to have roughly equal population, and I hear Osha is a little lower.
Palenque is the LEAST populous PvE server, so Eledhwen maintains perfect consistency.
Edit: I checked last night and found Artemis, Govinda, and Osha "Crowded". It seems the rumors I heard about Osha were inaccurate (as most rumors are), and perhaps Reni is the second-lowest populated PvE server.