I don't think I had a favourite book as a child. I do remember having a really nice teacher at nursery who used to read to us. I think that this enjoyment of being read to is the main contributing factor to me being such a sloooooowwww reader, as I avoided independent reading whenever I could.
However, books I can remember enjoying reading include Percy the Park Keeper and The Animals of Farthing Wood.
Recently for my own pleasure I have started to read Tinker, Tailor, Soldier, Spy. I have also started reading Bertrand Russell's History of Western Philosophy. Finally I have also been re-reading a few short stories by Jeffrey Archer. People may laugh at me for doing this but I think he's a brilliant storyteller! It also is easy reading which is a bonus.
I can't read one book at a time. I have to have several on the go at once. Anywhere between 3-5. This approach to reading may make it a little bit more difficult to follow what is going on but I find it keeps everything fresh which means I read with more interest.