I want to talk about the books I enjoyed instead, but I think we need another topic for that. I've such a soft spot for the books though, especially the ones that are like the literary equivalent of junk food, that you can just devour in a few hours, rather forgettable, but fun for the moment. .
While Twilight was after my time, I did read other vampire books in my teens and they were equally as cheesy. (Although admittedly a lot shorter). So I think I've no leg to stand on for criticising it. (Especially since I've not read it.) I do seem to recall reading a series with a time-travelling last vampire, who was best friends with a god, and who romanced a ghost, that may have been her reincarnated dead husband, and whose daughter (who insta-aged) was some sort of evil goddess of destruction that may have done battle with Jesus-reborn. BUT! my memory is super-fuzzy.
I think, nothing to be embarrassed about. If it's fun, it's fun. I find something tremendously comforting in reading young adult books, sometimes. I like how they tend to be shorter, and so less padded, and while often the world building is shaky, it's still fun to see ideas implemented. And if I don't like the book I can just move onto the next one.
I haven't read either. I did attempt to read The Dark is Rising, several times, and failed miserably. I just didn't enjoy it, and I liked a whole lot of other fantasy. I suppose I'm not a great one for classics, or literature though. (https://forum.choiceofgames.com/t/literarature-science-fiction-and-fantasy-books) I've also not read Harry Potter.
And on topic, I didn't particularly like Phillip Pullman's Northern Lights books. I may have been too old for them by the time I read them. Although I guess that doesn't count as worst. I generally don't finish them if they start out rather bad. I'll read a few pages and that's that.