I have used Zulip. It was fine in an environment where it was used to communicate among coders with a pretty rigorously defined and well-tooled workflow where i

I have used Zulip. It was fine in an environment where it was used to communicate among coders with a pretty rigorously defined and well-tooled workflow where integration with JIRA and github are important. In this environment it doesn't matter that less geeky users will find it less friendly than Slack, and coders are always using PCs or Macs and don't care that the Zulip mobile clients are ugly. I'm using Teams now with a small startup team. It's fine for that purpose. There aren't enough of us to annoy one another. Slack sucks in some ways. But maybe it sucks less. Most of my clients use Slack and are happy enough with it.