I've got a lot of books from my childhood, shelves and shelves full of them (I was a very avid reader when I was younger), so I'll only list off the ones that matter to me.
The Artemis Fowl series is a big one for me, it will always hold a special place in my heart. I practically grew up with those books, every time a new one would come out I felt a level of excitement that I could never forget for as long as I live. I read about Artemis's adventures well into my teen years, even now I eagerly await the next edition of the graphic novel adaptations that I can only hope is on its way. Also, I'm still waiting on that movie I was promised gosh darn it.
Next up is Warriors, this ongoing series could potentially be right up there with Artemis Fowl in terms of how much I enjoyed it. The only problem being that I really only care for the first series of books; the second one was good too, but anything beyond that is kind of meh. Even so, I absolutely loved these books, I used to stay up all night reading them. I don't hold it to as high esteem as I do Artemis, mainly because there's only a small portion of the books as a whole that I actually enjoy. The rest are okay at best, and the overall storyline has been twisted and stretched so much that it's hardly recognizable; there's really only so much you can do with the concept of clan cats living in the wild. If the series had ended after the first six books like I feel like it should have, I would probably have a much higher appreciate for it.
A Series of Unfortunate Events is worth mentioning as well, due to the recent Netflix series of which I am very much a fan of. It captures everything I loved about the books and improves upon it, which is exactly the kind of thing I look for in any adaptation.
Other childhood books include, but are not limited to, Charlie Bone, The Boxcar Children, Captain Underpants, Percy Jackson, and so on.