The Worthing Saga
by Orson Scott Card
I just finished it... it is the greatest book I have ever had the pleasure of reading. The explorations into humanity combined with the memorable tales and characters is... well perception altering.
Orson Scott Card always seems to masterfully gather philosophy and stirring tales under one umbrella, but with The Worthing Saga he really outdid himself.
I simply cannot imagine a book being better than this one. It will be hard to read anything else after reading the best.