I'm considering rolling here as well (2 50's on Master Dar'Nala) but when I was looking at server populations I noticed Gav Daragon has hit heavy on the status pages twice lately. Now I can't make my mind up.
But I assume Dalborra has a more Imp PvE guilds than Gav Daragon by looking at progression threads.
Based on the people feedbacks on the forum, the population shown on server status page is totally misleading. I suggest you can just roll a character on each server and do a "/who pit" etc. during your normal playing hours to sample the wz populations for yourself.