Several good nominations so far but I need to do some research before I decide where to put my votes. I can't go through the Baen Free Library at work and I know there are some good titles there (Honor Harrington series, Starfire series,
1632, etc.) Maybe
Wool would be a good starting point too. Decisions, decisions...
I really like
The Martian, but it has been read by a fair amount of people recently, so I suspect most people have written their comments in this
thread and we might end up with just a re-hashing of that.