Element is one of several free and open source Matrix clients.
Vector Limited is a company funding the development of the Element client, that also sells a Matrix homeserver.
There are several other free and open source Matrix homeservers.
You DO NOT NEED to pay a dime to Vector Limited for a Matrix homeserver, or use the Element client.
Meanwhile, XMPP is a “built by committee” nightmare, with a committee that didn’t commit (pun intended) to basic features, leaving file transfer, audio, or video calls, to be defined as “protocol extensions” (aka: incompatible) by each client.
TL;DR: use Matrix, with the Element client or any other, leave Vector Ltd. for the businesses.
Let’s clear something up:
You DO NOT NEED to pay a dime to Vector Limited for a Matrix homeserver, or use the Element client.
Meanwhile, XMPP is a “built by committee” nightmare, with a committee that didn’t commit (pun intended) to basic features, leaving file transfer, audio, or video calls, to be defined as “protocol extensions” (aka: incompatible) by each client.
TL;DR: use Matrix, with the Element client or any other, leave Vector Ltd. for the businesses.