This isn't really important or anything, but I've already got 20 names I don't want to take off my favorite authors list, and more I want to put on. If increasing the number allowed would cause screen-space issues, you could probably implement the favorite authors list as a drop-down like the comics list.
I cranked it up to 40. The favorites list seems to wrap reasonably nicely, so it doesn't look too horrible. I had just assumed nobody would have more than 20 favorites. Wrong again.