My guild is strictly social/ casual, however we are rebuilding and have quiet lulls at time. We utilize both gchat and Discord, I would prefer not sticking to one and ignoring the other, I tend to lean toward the ‘talk in gchat when in game and discord when offline’ kinda vibe, personally. Keeps people connected if they so choose to be.
We have retired from progression content, so that will never be an issue. I still think my guild might be a bit quiet for what you want currently, but feel free to take a look or message me to chat more.