Depends on what age we're talking about. When I was real young, it was the Runaway Ralph books, James & the GIant Peach, & Judy Blume "Fudge" books (Tales of a Fourth Grade Nothing, Superfudge, Otherwise Known as Shiela the Great, etc).
A tad older and I was all about Encyclopedia Brown and the Choose Your Own Adventure Books.
Somewhere around 4th-5th grade, my teacher had us read a horror book called "The House on Hackman's Hill" and I absolutely loved it. Would love to read it again.
In early middle school, it was the Hardy Boys books. I'd check out several at a time from the library and read one a day.
Soon after that, I left books behind and went to magazines - baseball cards, BMX, working out, and then cars (going through high school & college).
Micro-Wiggy (my 7-year old granddaughter) has to either read or be read to every night for school, so this week I took a page out of my childhood and started reading her a chapter per night from "The Mouse and the Motorcycle" (the first Runaway Ralph book), as I loved it when our teacher read it to us at that age.
She's loving it.