Dune

Some books are classics for a reason, and this is one of them.

Both the enormity and the density of the world building in this story are breathtaking, and the suspense of political intrigue keeps the reader turning page after page. There were some outdated concepts present that caused it to show its age-- the very evil villain is the only fat person as well as the only character who is anything other than heteronormative, among other things-- but they weren't enough to jostle me out of the story. The mysticism of futuristic religion intertwine with unknown technology and guerilla warfare to weave a work of art that feels ancient and visionary at the same time. Dune is an epic, it is exciting, and I would read it again. 
Readers should be warned that it is almost 700 pages (including appendices) about the intergalactic drug trade, and is therefore not for everyone. Fans of politically driven plots like The Queen of Attolia series by Meghan Whalen Turner, or other classic science fiction like Star Wars will enjoy this book.