Harry Potter isn't exactly that great. It's simply too easy and simple. The story itself, if you read carefully, is ironic, oxymoronic, and childish. It's intended for KIDS to read anyway.
Lord of the Rings is way better. The book itself is 100 times better than those lackluster movies. The movies simply made it "cool" by making things so fast and deliberately deleted many important parts from the book. One cannot understand what Middle Earth is just by watching movie, you got to read the book.