Basically what Suicyde said- Elendilmir is bouncing with PvMP 24/7, very much due to our international community.
However, due to the new content update, PvP is going to be a little quiet for a couple weeks, so whichever server you choose, give it until, say, the first week of October and see what the PvP is like then, when all the hardcore PvPers are bored again with PvE and come back to the Moors.
Elendilmir (the raid toons): LAERWEN, 80 htr ♦ OLORIEL, 75 min ♦ AETHELIND, 75 capt ♦ ROSALLA, 75 burg Landroval (the RP toons): LAERLIN (Bio + Drawing) ♦ AETHELIND (Bio + Drawing) ♦ NETHAEL
Elendilmir will be more active than Riddermark for a while to come, I think. So far Riddermark is a much smaller population server than E, with most of the growth coming from Free or Premium players. There are some long time subscribers/lifers that rerolled on Riddermark for PVMP, but some of them didn't seem to understand the Free/Premium can't PVMP - ie, that you must plunk down the $15/mo (or be a lifer) to play PvMP as either a Freep or a Creep. I think that will slow the growth of PvMP on Riddermark a lot.