I teach reading and my favorite books tend to be "Young Adult" novels. I'm completely addicted to books and bad things happen to my credit card balance if I'm let loose in a book store for too long.
Like most of you, Harry Potter, LOTR, Narnia, the Pern series (until they started going downhill--I think All the Weyrs of Pern should have been her stopping point).
I liked Mercedes Lackey's Arrows of the Queen, Winds of Fate, and even the trilogy about Vanyel, but again, the Valdemar books got weird and unwieldy over time.
The Little House series
I liked His Dark Materials--or at least, the first two. The last one got a little too hateful for me to really enjoy it.
The Ender's Game books--though the crown jewels are Ender's Game and Speaker for the Dead. The Bean series, well...the first one was good, then it got a bit bloated, not as fun.
To bring in a whole 'nother category, I like some cozies as well. I've read all the Susan Conant ones (as annoying as her protagonist is), the Carol Lea Benjamin series, Brother Cadfael, the Laurien Berenson series, the Elm Creek Quilters, Erlene Fowler's series, and most of the Miss Murphy series (they get worse later in the series, unfortunately).