I have given some lists of our favorite books in the past. My boys were younger. See here for a few posts.
But if you have a son who is learning to read and ready to move past the easy Dr. Seuss-like books, I highly recommend a series of books about Billy and Blaze by C.W. Anderson. These are the first books my 6.5 year old son has been excited to read on his own.
We got them from two different local libraries.
They were written in the 1930s. So they are good, classic books that may not be politically correct (they mention Indians), but both of my boys really like them.
This guy isn't reading them, just looking at the pictures.
If you want to order them from Amazon, here is the link (affiliate link):
And if you're still on the learn to read stage, try this book. We used this phonics-based approach; I highly recommend this book: