If by positive impact you mean most enjoyable, then: The Godfather, Mario Puzo (Film good, Novel excellent) Anna Karenin, Leo Tolstoy (Best novelist ever IMO)

If by positive impact you mean most enjoyable, then: The Godfather, Mario Puzo (Film good, Novel excellent) Anna Karenin, Leo Tolstoy (Best novelist ever IMO) Rendezvous With Rama Series, Arthur Clarke (Great) Replay, Ken Grimley? (Cool story)