Books

It's not an area I know deeply, but it's my understanding that certain fonts are more generally "legible" than others (for most people). This study found Arial and Microsoft Sans Serif to "be good and legible fonts" and Tahoma to perform poorly. But overall conclude that as long as people are literate, it doesn't make that much of a difference.

On a personal level, I do find certain fonts easier to read (especially for complex, run on sentences in journals) but when reading a novel a thematic font can help set the tone. It can even slow down my temptation to skim read and force me to focus on each word, which can be satisfying. So, it's part preference and part asking what you want the font to do for you - bland, familiar, accessible, easy to skim over? Arial is a good bet. Don't want people to fee like their in the office while reading your novel? Go with something else.