Depends on if you mean the best to be read by children or the best to be read by adults. As an adult, my favourite children's book is The Adventures of Winnie The Pooh. For young children, I think picture books like The Hungry Caterpillar or Peace at Last are some of the best.
There are so many out there!
I don't think it comes down to the best, after all as I grew up I was introduced to Bar Bar the Elephant.
I remember so well how I totally hated this book.It made no sense to me 'why'?
An elephant would be dressed up....and it made me cry.
Children are sold short on their intelligence, and we should encourage books that are light hearted, but more to something they will not have too many conflicting images.I think the best way is to see what your child loves to look at.Pictures I believed tell part of the story, and can be so powerful.
A lot of parents forget that key factor.
We should be allowing not just the words tell the story, but the pictures.
Look carefully at them, before buying a book.Then read the content, and if the two 'marry-up'', your one a winner.I absolutely love Pater Rabbit, even though the rabbits have clothes...because they look so gentle and sweet.a child will show you what they like, and you go from there.
Shaun Tan has written and illustrated some very thought-provoking children's books (such as The Arrival and The Lost Thing) that are interesting for both children and adults. Jackie French is another favourite Australian writer, and has written some very good books for young adults, many which have a historical theme.