Last I looked, only rocket.chat had a sane, minimal docker-compose setup that worked for getting started. I'm not thrilled about the mongodb dependency - but my overall impression of rocket.chat was very good. And the rest api is well documented and easy to work with.

It may be that zulip has "scaled down" a bit now - when I looked, it seemed you got the complexity of serving 10k users even if you only had 100s.

(Not meant as a dig at zulip, I think it's awesome that the project was made open source!)