I’ll go with the low-hanging fruit: Mein Kampf. I’ve read it, cover to cover. As a piece of propaganda, it’s good. As an example of good writing? Absolutely not (though I will admit I have only read it in translation). Oh, and the whole fascist, racist, and generally shitty worldview of the author that he infuses into the text. And the fact that the author is literally Hitler. You 5-star that book? You’re a Nazi. Period. And as a Jewish person, I don’t look too kindly on them.
His books are definitely fun, and I like how descriptive he can be. I would check out Deception Point if I were you.
I enjoyed Dan Brown when I was younger. Cheap thrills mixed with some (fictional ) culture. Deception Point was definitely his best.