...I've been deeply researching Discord alternatives for the better part of a year. Some of my colleagues may think me a bit obsessed about the importance of a "chat app," but I'm convinced that the communication mechanism for online communities is critical to their success. Choosing a new one could be the a matter of life and death for the community. This is a decision we have to get right the first time.
So here, humbly submitted, are my rankings of many of the Discord-like alternatives for maintaining online communities.