Our community uses both Discourse and Discord 
They serve 2 different cases - our forum being the place for community support, while Discord being the social space, as it leans towards having a more “real time” and social side to the community.
I wouldn’t say one is more popular than the other, more that they have different use cases and serve each accordingly. We do notice however people are creatures of habit, and if they have a technical question, they will ask in Discord, regardless of the forum being the ideal space.
This definitely sounds like something our team might be interested in hearing more about 