Element Server Suite, on the Matrix Network. Until Nostr is ready and capable for these use-cases, it'll be our go to, and has been for the past 4 years since we moved our Gaming community off Discord and family off other chat apps. Hosting a server is super easy now, and in just a year it's night and day compared to just a year ago as they nail in the spec for Matrix 2.0 -

GitHub

GitHub - element-hq/ess-helm: Element Server Suite Community Edition

Element Server Suite Community Edition. Contribute to element-hq/ess-helm development by creating an account on GitHub.

We federate with other Matrix servers and communities.