I'm building a student community and after while I stumbled upon zulip https://zulipchat.com. I think it's the most decent organized chat out there. Channels (aka streams in zulip terminology) can have topics on each stream so it's super easy to stay organized.
While branded as a "chat for gamers", the screen sharing, sound, conference and channels quality and tooling is far more versatile and superior to Slack.
