A goat lock looking for a home? I wish you luck! I’m going to mention a few guilds I know of that you may fit in with/may be worth a good brows! I hope you find the right one for you! All are decently active/casual on the content side of things (to my knowledge).
The Antoran Harbingers:
The Antoran Harbingers are very numerous in the city and outside of it. From what I understand, they have a distinct structure and way to grow within while I believe being pro-Legion? I don’t know as much, but many are quality RPers.
The Legacy of Arzaal:
I am not sure if this guild is still active, but if your character is Anti-Legion it may be a great fit while still being a warlock.
Sargerei:
This is another pro-Legion group, but newer on the forums! I have not seen them around in game but figured mentioning them could be helpful!
The Shadow of Lordaeron:
This is my personal guild, you may find that it could potentially be a good home for you, depending on circumstances!
There are also a few other groups around that I’ve seen in game. You may have some good luck just browsing around Stormwind! I hope this has been helpful.