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.
Playground. I cannot overstate how badly written that book is. It covers the darkest subjects(nothing wrong with that), but with a writing level akin to that of a 6th grader. I absolutely despise the book for its ability to take an interesting premise and squander the fuck out of it.