Hi - I want to start by saying that I really love this site and the work that so many people have put into making it an incredibly valuable resource. I worked off of the Writing guide to make a writer recently, and I found some things that I think could use a brush-up.
The writing genres on the site are evaluated by straight up value for the book written, but of course, longer books take longer for your sims to write. To maximize a writer's income, it's the value per page that counts. And when the value per page is calculated, it turns out that Masterpieces (while great to satisfy high-value wishes for your Sims, and nice to have around because of the moodlet sims get from reading them) max out somewhere between 6 and 7 simoleans per page written, Vaudevilles garner upwards of 8 simoleans per page written (the value given for Vaudevilles on the writing genre page is low, 8k is the norm for me).
Also, Children's books are listed as Medium-High, but at almost 5 simoleans per page, they are the clear winner per-page of the shorter books, and they beat out both Mysteries, Romances and even satires as well. A sim can churn out two childrens' books per day, getting the prolific author challenge quickly and very profitably.