I like 3 because is clearly shows there are three books. Some of the others make it sound as though it is some long slogan and not three distinct things.
5 for the image and colors, 3 for the lettering and general organization of space on the cover. 5 if you want it to pop out - somehow gives out an adventurous vibem. 3 if you want a more refined, posed look. All others are nice too! These two just really stood out the most to me! :)
