I actually prefer XMPP. It’s also less of a hassle to set up than Matrix and the protocol is much more mature. There are still issues, but it’s rather functional for audio and video calls (if you’re using a supported client).
Edit: For clients, I use Cheogram on Android and Profanity (which is a TUI) or DinoX (for calls) on Linux.
I actually prefer XMPP. It’s also less of a hassle to set up than Matrix and the protocol is much more mature. There are still issues, but it’s rather functional for audio and video calls (if you’re using a supported client).
Edit: For clients, I use Cheogram on Android and Profanity (which is a TUI) or DinoX (for calls) on Linux.