I had a lot of favorite books growing up. My mom was a librarian and my dad was an educator and bibliophile so there were many choices. Every summer my mom would make us a list of the books she thought we would like to read and bring them to us a few at a time. I loved the Wrinkle in Time series and the Earthsea trilogy and of course all the Tolkien I could find. I read all the Chronicles of Narnia books and a fantasy series by Mercedes Lackey that involves telepathic horses.
The books I loved to have read to me as a little kid are some of the ones I read to my kids too. In looking these up I figured out that they are both written in the 30's so they were probably favorites of my parents as well.
Mike Mulligan and his steam shovel was a favorite. It is the tale of a guy and his steam shovel. They work tirelessly and in the end he digs a foundation so deep that the steam shovel gets stuck and becomes the boiler for a building. Sorry for the spoiler.
One of my all time favorites was Ferdinand the bull.
I read this to my kids everyday for a while. So much that I stopped reading the right words and just made it up spawning cries of "no dad that's not what it says!". And I read it in a funny accent which was kind of a cross between Cheech and Jamaican. The giant copy of it is still in our living room just waiting to be brought back into service.
I look forward to seeing others picks