Orson Scott Card: Ender's Game
The best science fiction book ever written. If you haven't read it, do so immediately.
J. K. Rowling: Harry Potter and the Sorcerer's Stone (Book 1)
I'm sorry, I'm a sucker for this kind of book. I love this one and the next four. And the movies too. So there.
L.M. MONTGOMERY: Anne of Green Gables
A childhood favorite, but still a series I pick up and reread every few years. I just wish I could find my "kindred spirit" like Anne did.
JEAN M. AUEL: The Valley of Horses
My favorite of this (so far) five book series, although I love them all.
ANNE MCCAFFREY: The White Dragon (Dragonriders of Pern Vol 3)
My favorite of the trilogy that started my love affair with the fantasy/sci-fi world, Pern.