This is for screenwriters only, but John August, professional screenwriter and a self described font nerd, has been long dissatisfied with Final Draft Courier font and so developed a variation on the font that reads so much better… information here at Introducing Courier Prime.
He lays out a lot of history and reasons behind his move, and the app is free and easy to install (there are some issues if one has a PC and uses Windows, I hear) but having tested it, I love it.
The thing you most want as a screenwriter is an easy, flowing read and Courier was always, well, a bit challenging in that regard. This app makes it still Courier but much easier on the eyes.
So if you’re a screenwriter, download it and give it a shot. Personally I love it.