If you’re looking for a neutral guild, there are loads of options! Most prominent in my opinion is Blackwater, led by Persefani. Here is their forum link.
If you’re looking for darker rp, as a Cultist of the Damned or Scourge, my guild may also be up your alley. You can find more about us here:
You’ll of course find a few more across the forums, so keep a look out! Happy hunting!