Dune (Dune, #1)
As good as classics like The Name of the Wind and The Lord of the Rings.
The world is vast, which can be tiresome at the very beginning but it is really fast to involve yourself with the book. It also uses unusual elements to build a sci-fi story. Shows how religion can easily be influenced by human beings and yet can sound messianic in the long term. It combines a lot of rare topics to create a memorable story.
The thing that has impressed me most was the relation with water. It shows how something extremely necessary when in shortage can shape different aspects of culture, going from religion to what is the meaning of respect.
Really worth reading!