My group of friends still uses Mumble for talking to each other. It is hosted on our own server. It has transports to all sorts of messengers.

I use discord for some things, but only from a browser. Wouldn't want to use it professionally, although it is relatively decent.

Speech quality is far better on mumble with less latency, because the server is in near proximity.

edit: Don't know about Mumbles text chat, it is rarely used.