Matrix is okay, hopefully will be better someday, but I've had a pretty good time with XMPP the last few months. If you stick to Dino and Conversations (maybe Gajim too), the OMEMO is easier and more reliable to get working than Matrix's encryption, and you can turn it off. I mainly use Matrix unencrypted because they don't let you turn it back off, and it feels like most of my contacts don't understand the device naming and verification stuff. (also sometimes device verification just doesn't work). XMPP is also a LOT less laggy. Closer to IRC feel.
I still use Matrix, but it's often frustrating with messages showing up late or out of order, and none of the clients feeling quite good enough yet. Especially if you use multiple accounts.
Every XMPP client I've used supports multiple accounts, but for Matrix I've only recently run into Quaternion which supports this, and I believe also Neochat (they both use libquotient), but they're still rough to use.
I wouldn't even consider options that aren't free software, and I'd also exclude signal because of them not putting their app on f-droid, not being properly decentralized, relying on a phone number, etc. (note that both email and phone number are optional for Matrix accounts)