Goethes "Faust" will always be in my top five.
For entertaining "The hitchhikers guide to the universe" by Douglas Adams and many books by John Irving and T.C. Boyle, especially "Hotel New Hampshire" and "Water music".

The only book that has changed my life was a rather lousy written book with great pictures of Tasmania which made me pack my bag and travel thru Australia for almost a year and visit the places i've lived the first four years of my life.
I came back rather different to how i was when i left.