Okay, here's my blurb on reading. You do create readers. There are no ifs ands or buts. Children will only learn to love reading if a) they are read to; b) they are surrounded by good books (the fluff and the classics because the fluff is brain candy and just as enjoyable as real candy); c) they understand how integral reading is to their quality of life (reading signs, labels, price tags, etc.); and d) they SEE THEIR PARENTS READING.
Granted, your children are going to have their own level of interest. Derek didn't venture out of sport books for a long time and then he dove straight into Louis L'Amours--but he read. Wyatt didn't read as much--but he read. Ethan is one of the most well-read people in our family because Mom paid him to read out of his comfort zone. Youngest child syndrome and all that--but he read.
It sounds like you guys are comparing your own children to each other. Instead, spend a little time comparing them to the average student in the system. One year I asked all my students who had read a book for fun that year. I had TWO raise their hands. You don't have any clue what a true non-reader is like because it is impossible for you to produce them because of how invested in literacy you are.
So, pat yourselves on the back and don't worry about it much. Kami needed to worry about it because Ana came from a non-literate background and needed some serious prodding. She's come a long way too. Your own children can develop their reading inclinations more naturally.
As for quality vs. not quality books--as long as there is nothing morally questionable any book is great if your child likes it for free reading. For school--they need to be assigned out of their comfort zone, but free reading is free. Pure pleasure like fine dark chocolate.