I know I'm in the small minority of Discord users who mostly uses it as a voice chat room while gaming with my friends, but for that use case the best alternative I've found seems to be Mumble.
I recently set up a Mumble server on my home server and it seems great so far, was able to get my friends connected pretty easily. We'll see how the voice quality and latency compare to Discord.
> I recently set up a Mumble server on my home server
That makes you an even smaller minority unfortunately. Most people are not going to set up a home server.
> small minority
Huh. I’d have said majority. It was always my impression that a) gamers make up the vast majority of discord users (with all their gamification and gaming features), and b) that gamers mainly care about voice chat (which is what people almost always talk about when it comes to discord and gaming).