"We've switched to Signal, but we mostly do one-to-one conversations"
And now you have a new problem. Signal only works on phones making it and most of it's competition useless for most of Skype was good for. And then we have hangouts, which chokes on my 1080p webcam (worked great with Skype even on Linux).
Only thing I have found that looks promising is Ring.cx but no one uses that and it's still in Beta.