I love nothing in my life more than Harry Potter. It's changed my life and made me a much more interesting and better person. The books are the greatest in the world.
But on a cinematic look, the Lord of the Rings movies are by far twice as good, no arguments. They are so powerful and...I can't explain it well, but they have extreme dedication in them (not that HP doesn't, but...) Lord of the Rings will be the ones looked back upon as great achievments in movie making, not Harry Potter. The greatest thing about Harry Potter is the books by the amazing JK Rowling.