For everyday writing I like to use MessagEase. It’s highly ergonomic thanks to the 3x3 grid and deeply customizable. I’ve been happily using it for over a decade now (it continues to receive updates) and for the past 8 years I’ve been able to touch-type on it without looking at my fingers
The documentation is all in-app, so I’ve taken the liberty of screenshotting the relevant pages for illustrative purposes: