[someoneelse9]

XMPP server is slightly easier to setup and it requires far less resources than matrix. I think that in the server aspect XMPP is superior, in both performance and scalability (ejabberd).

The client setup in XMPP and Matrix seem to have the same usual steps (username and password). No big differences here, other than Element defaults to matrix.org to create an account (which contributes to centralization).

I'd say that XMPP clients are generally better than matrix's ones. Maybe because matrix is an immature and younger protocol, but Element seems to be the only client that implements everything and UI is confusing and it's electron.

And a personal preference, I like using my GPG keys to encrypt my conversations when possible in XMPP. This wouldn't be possible in matrix.