None of these covers shows "the" Dune font, for me. The first edition of Dune had a very stylized calligraphy that looked like arabic. I remember it vividly since my dad had this book in the living room, among others; and when I was learning to read, this was the only cover that I couldn't read at all. (It was a translation, but with the same cover.)
EDIT: The covers of some modern french translations are also incredible. Just the four letters D U N E, which are exactly the same shape but rotated 90 degrees. It's an incredibly simple and effective design.
These letters are shown on the wikipedia page about the novel: https://en.wikipedia.org/wiki/Dune_%28novel%29
EDIT: The covers of some modern french translations are also incredible. Just the four letters D U N E, which are exactly the same shape but rotated 90 degrees. It's an incredibly simple and effective design.