Michael Descy has written a great piece about finding a writing font, and why it isn’t just a waste of time.
Choosing the perfect writing font is a classic way to procrastinate—but it is not a waste of time. Fonts are important. A good font is not only highly legible, it also conveys a subliminal emotional effect on the reader. Naturally, it follows that it will also have similar effects on the writer. A good font will make you feel better while you are writing—maybe because you can read it more easily, or because you find elements of it, its curves or serifs, aesthetically pleasing. Whatever the reason, picking a font that is pleasing can have a profound effect on your writing.
He goes into detail on what makes a good writing font, some considerations you will have to make, and also a bunch of great suggestions.
For myself personally, I’ve always used a monospace font to write with. I once saw someone write about it before, although I can’t remember the source, but they explained how they used monospace fonts while they were writing/editing, and a sans-serif for previews. This is similar to how I feel myself.
Because I write everything I do in Markdown, it still feels like I’m writing code, not a programming language, but still something that has to be deciphered before it’s fit to be seen by anyone else. And for some reason, monospace fonts use feel like they represent something that’s in progress.
So, the font I use for nearly everything is SF Mono. It’s the monospace version of Apple’s San Francisco font, and it’s been my favourite ever since they released it. However, it requires some fiddling to have it installed like a regular font. Before that I used the pretty similar, Andale Mono.