Selbina, Besaid, Palamecia, and Wutai I believe have good populations. I'm on Selbina and I can tell you there are shout groups for parties and what not on the weekends especially with a good populations always on around leve reset time (which sucks for some of us who would like to do behest now haha) But gridania and Limsa are still less populated lately on Selbina I've seen a lot more people in those areas those not sure if they're new or something.