As a child of the Harry Potter generation one of the HP books was bound to be on this list, though I never thought I'd choose this one because The Goblet of Fire is probably my least favourite book in the series. If I really had to pick a least favourite. I still like the book a lot.
I'm not even entirely sure why this book is my least favourite. I can tell you exactly why The Order of the Phoenix is my favourite book in the series: Dumbledore's Army; Tonks; Luna; the return of Sirius and Lupin; the Order; the battle in the Ministry and Umbridge. That's right. Umbridge. Otherwise known as the villain we all love to hate. I mean if we're completely honest I think most HP fans, myself included, hate Umbridge more than Voldemort.
The Order of the Phoenix is also the first book in the series that feels really different to the first. It's so much darker. That's not to say The Goblet of Fire isn't dark, but I always found that the fourth book in the series was an odd mixture between the more child-like tone in the first three books and the darker tone in the latter three. In many ways it's a very in-between book, which I think is the main reason why it's my least favourite.
But like The Magic Finger, the first book on my list, The Goblet of Fire is special to me in that as far as I can remember it's the first Harry Potter book I read alone. The first three were read to me by my Dad when I was little. It was also the first book I ever read where not only did someone die in the very first chapter, but later a character who was still in school died, too. For no other reason than that Voldemort is a terrible human being.
Cedric Diggory's death has always stayed with me, and even though I'm in my twenties now it still makes me sad. It disturbed me, when I first read The Goblet of Fire, to be hit with the realisation that just because someone is young and still in school doesn't make them immortal or untouchable; that they can still just be in the wrong place at the wrong time, at the mercy of the wrong person.
I'm fairly certain this was the first book I read in which more than one person died, and also the first book in which those deaths just felt... pointless. Not in a 'I don't understand why J.K. Rowlng made that decision' kind of way, but in a 'how could Voldemort murder them? They didn't do anything!' kind of way.
This book gave me a lot to think about when I was still quite young, and I'm glad it did. It might not be my favourite book in the series, but it taught me a lot.