Roald Dahl! the writer who introduced billions of kids to psychedelia: which of his is your favorite and how has he influenced you?
It's more his collection of short stories. A simple setting, minimal characters and a twist you just don't see coming. The story heads in one direction and then smacks you with another out of the blue. I especially liked the story about the bed and breakfast where the owner... Well... Won't say what. Or the story (also filmed and included on the Psycho blu-ray) where the woman kills her husband after he tells her he is leaving her. Great stuff.
If it HAS to be his children's story though - The BFG. The imagination there is great, as is the story. Light where it needs to be and incredibly dark when it wants.