This is entirely the wrong community for this answer, but I've used the pro version of Textra for 10 years now. One time payment (10 years ago), updates every few months, lots of features, but they don't get in your way if you don't need them.

The main feature I use is "delay send for 5 seconds" to allow me to catch all my spelling and grammatical errors after I hit send , but the rest of the UI is pretty well thought out.

One of the very few commercial Android apps that I'd recommend to someone.