I like to read a lot of different things: Stephen King, Dean Koontz, Patricia Cornwell, Nelson DeMille, Douglas Adams , Michael Chricton, and so on and so on...
I like some classic stuff as well. (If you've never read "Frankenstein" by Mary Shelley, you are doing yourself a disservice.)
I just recently discovered "Wicked" by Gregory Maguire which offers a very different take on a very familiar story. It's been developed into a Broadway musical but with some pretty big plot changes.
I have to say that my favorite series has to be the Wheel of Time series by Robert Jordan. It's hard for me to pin down a favorite book in the series, but I am anxiously awaiting the final installment slated to come out October of this year.