Not sure that huge number of communication channels so important. Maybe telegramm channel will be enough, because it is most popular and simple to use. Better to have one channel with active users than 10 dead channels
Our Slack has 334 members at the time of this post and the Discord is at 20. Slack is particularly active, though Discord has been chatting steady since it started.
I've noticed that many people who join our Slack are surprised with how active it is.