If you’re writing a professional document, The AdWeek Copywriting Handbook offers you this counterintuitive but fascinating and helpful insight:

In tests of print-document legibility, serif fonts (like Times New Roman, fonts with decorative loops and strokes at the ends of letters) win over san-serif fonts (like Arial, with no decorative extra strokes). And they win big.

In fact, tests find that readers have five times greater comprehension of documents written in serif fonts.

The lesson: If you want to make your document easier to read and digest, use serif fonts.