I can only speak for the PvP servers. Venekor, where I reside, has a lower population compared to Nagafen (sp?) but that is actually preferred by residents of both servers. Nag is a 24/7 non stop PvP server for those that enjoy it. Venekor is a more casual, laid back PvP server. PvP is easy to be found but, not forced down your throat every time you step foot outside the city gates.
Venekor is labled RP.. however much like the PvE servers, its not enforced and as a result we have plenty of people running around with untasteful names and guild names. And, every once in a while you'll even run in to an anti-RP who is easily put on ignore.
Pardon me if PvP isn't your style.. but I wanted to stick it out there for people who may stumble upon this thread at a later date who might be interested in PvP. :)