Atlas Shrugged. After a few reads it's hard to place anything above Atlas IMO.
The Name of the Wind, &
The Wise Man's Fear
Both really good too, but I kinda think the underlying philosophy being espoused might be wrong. It doesn't take away from the enjoyment at all & the 3rd book still isn't out so I could be wrong & may end up plesantly surprised. But the writing is pretty incredible either way.
