How to find the "best" children's books

During a lull at the library yesterday, I began to browse around for "best of" book lists for children, middle-schoolers and teens. I know that such lists neglect many great books, and if you stringently sticks to a list, you might not find the best book for a particular child at a particular time.  However, for me, this is a good starting point/reference tool! 

Preschool and kindergarten
• Caldecott Medal and Honor Books, 1938 - Present
Full list (includes Honor books, book descriptions; divided by decades)
Printable list (Medal books list in reverse chronological order)

• 100 Books to Read Before Kindergarten  (Louisville Free Public Library)
Printable list


Elementary School/Early Middle School

• Newbery Medal and Honor Books, 1922-Present 
Full list (includes Honor books, links to book descriptions; divided by decades)
Printable list (Medal books list in reverse chronological order)

• (NPR) 100 Must-Reads For Kids 9-14 (chosen by NPR readers)
Full list/descriptions (includes book covers; divided by genre)
Printable list

• Parent and Child/Scholastic 100 Greatest Books for Kids
Interactive bookshelf (Appears on virtual bookshelf; lets you divide by genre, age group)
Printable list (shows recommended reading age group under titles)


12+*

• 100 Best-Ever Teen Novels (books chosen by NPR listeners)
Full list/descriptions (includes book covers; divided by genre)
Printable list


* Note: I'll do "Young Adult" books in a separate entry, to better divide them by genre and to include more contemporary YA novels.