I am sort of obsessed with children's books (as you can see by how many hubs I've written about them!), and my son is too, luckily, but I would say his favorites are always changing (he's 2 3/4). Right now, his favorite is Goodnight, Goodnight, Construction Site. It's really fun to read and the pictures are beautiful. He's very into construction vehicles right now, and they seem to be all around our town this summer, so it's perfect for him. I highly recommend it.