Another vote for Kurt Vonnegut as my all time favorite.
Also, old King is the shit. Check The Stand (books where everyone dies but a few people are the shit), or just about anything he wrote as Richard Bachman (the long walk, wtf?).
Two of the best books I've read are The Alienist and The Angel of Darkness by Caleb Carr. It's like Sherlock Holmes, but in New York in the 1890's. And they're chasing down sexual serial killers. Some disturbing shit in these ones. Haven't read his other shit.
The Pillars of the Earth by Ken Follett was fucking dope. It sounds stupid (a dude builds a bigass church in like 1100), but it's one of the greatest books written.
Dies the Fire (and the books that follow in the series) by S. M. Stirling is one of the best ideas for a book ever. In modern times, suddenly combustion and electricity stops working (no gas, no gun powder). Earth is thrown back to the bronze age, but with the remnants of modern days all over the place. Shit was dope.