Fiction books are often cited as being more entertaining than non-fiction books as you get to travel to exotic, sometimes alien worlds and the characters can sometimes be supernatural, with cool powers like flying or being able to heal instantly (vampires, anyone?).
But non-fiction books like biographies can be just as interesting if you're writing them about the right person. Check out this video to learn how to compose a non-fiction biography with tips.
This video provides guidance on how to write a professional biography.