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.