There are a couple I have in mind. Like many techies, I am a huge fan of RSS for content distribution and XMPP for federated communication.
The really niche one I like is S-expressions as a data format and configuration in place of json, yaml, toml, etc.
I am a big fan of Plaintext formats, although I wish markdown had a few more features like tables.
Xmpp definitely wins in privacy. What is there to privacy more than message content and metadata? Matrix definitely fails the second one, and is E2E still an issue for public groups? I don’t remember if they fixed that.
XMPP being a protocol built for extensibility means it will be hard for it not to keep up with times.
On your point of picking one or the other, I’d say pick the one you like and bridges will help you connect to the other. But XMPP came way before matrix, and I believe they fractured the community instead of building it.
There’s a good reason all the big techs built on top of xmpp (meta, Google, etc). It’s a very good protocol and satisfies modern demands very well.
Okay so how does modern XMPP protect this? When I last used XMPP, some (not all) clients supported OTR-IM, a protocol for end to end encryption. And there wasn’t a function for server stored chat history (either encrypted or plaintext).
Have these issues been fixed?
It’s not perfect yet, but it’s much, much better than the old days.
OMEMO is supported by every major client, and they interoperate successfully. Unfortunately, most clients are stuck with an older version of the OMEMO spec. It’s not ideal, but it doesn’t cause any practical issue, unless you use Kaidan or UWPX, which only support the latest version.
All popular clients and servers support retrieving chat history now too.
In practice, I’ve been using it for several months to chat with friends and family, and haven’t had any issues.