Like a lot of people my age, I grew up reading the Harry Potter books; I practically worshipped the things. Those were probably my favourite books growing up, they were the literature equivalent of Pokemon: everyone was into them, my parents both enjoyed them, and there were movie adaptations which (at the time) I loved.
Prior to that, it was Goosebumps. I'd save every penny I could find just to buy the next one in the series, and I felt so accomplished when I finally got a full collection...then Series 2000 came out, and it started all over again. I used to watch the TV series of that, too. They weren't particularly scary, but they were the cool thing in my social circle.
I also used to love reading the Horrible Histories and Horrible Science books. Those were quite popular when I was a kid too; my friends and I had almost a full set between us, and we'd swap them around regularly. We dabbled in The Knowledge and Murderous Maths a little as well, although not quite so much.