Well having played on a few other servers before coming to Virtue I can say without a doubt it is certainly the most RP active. So having said that, I don't think you can really go wrong by moving here 
I was planning on asking the same thing. It seems that by Virtue's forums, it is the de-facto and ONLY RP server. I am going to have to drop in and havea look see this very night!
Back wehn dat beta tingy wuz goins on da peepuls did one of dem vote tigies. Deys cided to makes Virtue da Uno Fish al arpee serber. Whale heered bout da Uno Fish so hims comed heer. Whale still lookin fer dat Uno Fish so hims kin eets it but it mus be sneeky cuz Whale no seeds it yet.
It was decided by a majority of the pre-release community that Virtue would be the unofficial RP server.
What does that mean? Not a whole lot really.. Its INCREADABLY unofficial.
There are a lot more RP'ers here from other servers, but not everyone on Virtue Roleplays (nor should they be hassled about it.) Announcing Virtue as an unofficial server just gave everyone who was interested a focal place to gather.
I hope if you do come to virtue, you have an enjoyable time and find a lot of people to share your stories with.
Thanks,
It seems a little bit like that from the amount of Virtue-related activity on this forum.
Playing on Justice at the moment, but want to get round to creating a more rp-oriented toon, so want to make sure it's on a good server for roleplay.