I have been reading Dune since there was only two books to read -- Dune and Dune Messiah.
My favorite book is Heretics, as the journey of Miles Teg as a type of everyman is second-to-none.
I really enjoy the new books by Brian Herbert and Kevin Anderson.
I feel that all of the Dune books that have been written by the Herbert father-and-son team of Frank Herbert and Brian Herbert have their merits. Brian Herbert does a great job, carrying on his father's legacy with a type of "genetic trust".
All of the books have there highlights, and there points of tediousness and randomness -- but overall, Dune is the best saga out there.