Family and a few friends, on own server.

It seems to be a good fit for families. Or rather, families are a good fit for any sane, sustainable technology. Long span of time, lots of mutual transparency, plenty of in-group communication inside and outside the chat technology.

No problems characteristic for big-tech (account seizures, hardware platform restrictions). No problems characteristic for free-for-all public servers (spam, vandalism).

I got into XMPP in just the last few years, after already using Matrix (and still using IRC also).

XMPP for me is mostly internet friends. It's quite popular on the fediverse (they also happen to commonly dislike Matrix, although many are on both like me). Lots of people who are into technology and anime, basically.

I've noticed most free software projects don't have an XMPP room unless they are literally XMPP projects like Gajim and Dino. Pine64 (as well as many other places) will have a bridge between IRC and Matrix, but I've only seen one or two IRC channels that also bridge XMPP that I can remember. Many people aren't even really aware of it. I don't know the actual stats, but it often feels like XMPP is actually less popular than IRC these days.

I think XMPP is more popular to use with friends and family rather than public channels. Btw you can join IRC channels from your XMPP client: https://joinjabber.org/tutorials/transports/irc/

I'm aware of being able to join IRC from XMPP, but the thing that still makes IRC the best for me is actually the client selection. irssi is just leagues ahead of Gajim, Dino, Profanity, Conversations, Element, Nheko, FluffyChat, etc. I really haven't seen any chat client nearly as good as irssi besides weechat. It's like no one who made good IRC clients left IRC, so there weren't people to make good XMPP or Matrix clients.

Friends and family all use XMPP via Conversations and/or Dino. I also join a few channels of FOSS projects on Matrix or IRC with a bridge. You can even bridge calls to SIP and PSTN via https://jmp.chat/.

I run my own server (any 5 bucks VPS can do), but there is a large number of public servers that also work good. Make sure to pick one with a good ranking at https://compliance.conversations.im/

I run my own server, I am talking to some friends on https://jabber.fr and I refer non-technical people (family, mostly) to https://quicksy.im.

(I will add that Jitsi Meet kind of counts as Jabber use, although not in the traditional sense)

Since WhatsApp changed its ToS last year I deleted all messaging apps except Conversations and started using XMPP exclusively. Basically everyone I talk to regulary is now reachable via XMPP.

I use Jabber everyday to talk to my partner and family. They use https://quicksy.im/

I use it for sms and phone calling through jmp.chat. Though I'm afraid that carriers are going to sandbag it if it gets popular.