So, I have a Threema license, but from what I’ve seen its encryption isn’t post-quantum. Signal’s encryption seems the strongest. I host my own matrix server.
Also, I kind of don’t care where the servers are or which provider it is. Everything is encrypted anyway.
I liked the Matrix because of all the kung fu karate fights, though I got to say the second one was the best, even though the third one had a Dragon Ball Z fight at the end