When I was in school, my favorite was Michael Crichton's "Andromeda Strain." Must have read that thing eight or ten times. Too bad the movie was such a dog...
Recently, I've set upon Robert Parker's "Spenser" novels. I've read them all, but my favorite is "A Catskill Eagle." Spenser is usually a pretty glib, snarky guy. Not in this one - he's dangerous, and the change of pace actually makes the other books better, because now you know what the man is capable of doing, and accept the glib and snarky more readily.
And last, I devoured Stephen R. Donaldon's "The Chronicles of Thomas Covenant" when I was in college - these were the height of fantasy writing, as far as I was concerned. The third and final Chronicle is being written now - eagerly awaiting to see if it matches up to the first two.
Favorite author is pre comb-over Dean Koontz. After that it was just rehashing old storylines and characters. I have two favorite books Battle Royale by Koushun Takami and (I feel a little gay admitting this) Snow falling on cedars by David Guterson, it is very well written and doesnt have the Hollywood ending.