I use Gajim on Windows and Linux, Dino when I need to call, and Monal on Mac. XMPP is older and less trendy at the moment, and it’s a large, partially fragmented ecosystem- that might hold back mainstream adoption. But it’s the horse I’d bet on long-term.
Seconding the XMPP reccomendation- I run Prosody, which has been rock solid and stays up even when other services I run go down. File sharing, E2EE, reactions, voice and video calls- everything you’d expect from a modern messenger. Cheogram or Conversations are great Android clients, and Monal is the iOS client I’d reccomend.
I use deSEC, a non-profit based in Berlin. Has been an excellent experience, and very easy to use for DNS-01.