Redacted
If there is a desktop client you like, but it doesn't have E2E, you might consider using it with pantalaimon. I'm using ement.el successfully this way.
There is a good TUI client called gomuks, if that is something you would be interested in.
Otherwise, on desktop, I use a web client in my existing web browser, which avoids the extra overhead of electron. Element is fine, but Cinny is also nice and a bit lighter.
I also agree that FluffyChat is the nicest Android client; Schilde Chat is also good.
Well, well, I, I even failed to get a matrix account :-) I tried several times, but I did not get enough google credits or whatever. So I have to hang out in the bar, while the chatting is going on in the Matrix room. Fine with me.
How flexible is the matrix protocol? Can one take an existing IM client (like pidgin) and write a matrix connector for it?
Just out of curiosity, what's your opinion on XMPP/Jabber?