As with most sci-fi the author gets loopier in the later books. That being said:
Dune: masterpiece of philosophy, one of the best books ever put to print
Dune Messiah: a worthy sequel and must read after the first book; completes Paul’s arc
Children of Dune: more plot driven than the first, but still thematically rich and entertaining.
God Emperor of Dune: the most divisive of the books: you love it or you hate it. I am in the love it camp, the book is unhinged and the themes are marvelous. This is where I’d stop a read of the series.
Chapterhouse and the other (Heretics?): forgettable in my opinion, simply because I’ve forgotten them. Later book fan opinions welcome.
anything Brian Herbert: not terrible but not awfully good either. Makes for decent light reading I guess, and there’s good lore building in some of the books despite some unforgivable retcons (Agemmemnon, sigh)
Heretics and Chapterhouse are also weirdly horny. Sure, sex was always a big part of how the Bene Gesserit operated, but when they were made the hero faction it got… weird…
Those two books also fully raised Duncan to be the main character, though, and they introduced Miles Teg, so they have that going for them.
As with most sci-fi the author gets loopier in the later books. That being said:
Heretics and Chapterhouse are also weirdly horny. Sure, sex was always a big part of how the Bene Gesserit operated, but when they were made the hero faction it got… weird…
Those two books also fully raised Duncan to be the main character, though, and they introduced Miles Teg, so they have that going for them.