Fair enough — ‘The Magician’s Nephew’ really can’t be topped!
I was familiar with “The Lion, the Witch and the Wardrobe,” as a child, and the Christological symbolism was obvious enough, but I never read the other Chronicles back then. Years later, after having read many of Lewis’s more direct and ‘serious’ apologetics, I went back and read all of Narnia. It was amazing to see how he folded some very deep observations and concepts into the story...and yes, “Magician’s Nephew,” is fantastic...