Original answer coming through!

Harry Potter.

Like many kids, Harry Potter is what got me into reading more books (even though I read less than I'd like to). The reason I place Harry Potter above many other probably more intelligent novels is one thing: characterization. What the novels may lack in plot (it really could have been four decent-sized books), it make up for and then some in giving us interesting and "real" characters. Over the course of seven books, these characters better have some growth, and they do! Character growth feels so natural in this series. I enjoy reading these books because more than any other because no other book has given me such rich characters to join in on adventures like Harry Potter does here. It also helps that the adventure itself is a fun one, too.