I'll read almost anything, so bear with my rambling list...
Douglas Adams- He can really tickle my funny bone.
Piers Anthony Talk about your mischevious humor. I actually preferred his "Incarnations of Immortality". They were really captivating.
Clive Barker- He can make you hide under the covers, shuddering. *Delicious* The book I loved the most from him was Thief of Always. It's great for children and for adults.
Orson Scott Card- I loved him for the Alvin series... I hear that the Ender's series is also great. I have to find it and read it soon.
C.J. Cherryh- Rusalka was incredibly touching...
Michael Crichton- I used to like dinosaurs until I bumped into him.
David Eddings- He has a wonderful wit. His characters are fun to be with.
Robert Heinlein- I particularly like his views on relationships. Right, Corn?
Robert Jordan- He writes good stuff, just terribly long...
Stephen King- Even when scaring you to death he can make you laugh. There tends to be a dark humor that's contagious in his stories. His latest stuff, like Insomnia and Dolores Clairborn, while still good, aren't as frightening as usual.
Mercedes Lackey- The Last Herald-Mage can break your heart. I love the openess you can find in her books. She's willing to deal with all sorts of different kinds of people.
Anne Rice- Give me vampires or give me death! er, undeath? I love vampires in general, but Lestat is a notch above your ordinary vampire. However she has other great books... Her Cry for Heaven was wonderfully depressing, and there's always Lasher to entertain us.
Judith Tarr is another great author which can drag you into her dreams.
Tolkien- Just my preciousssss....