So far it's been World War Z, hands down. The book lends itself to the audio format extremely well due to the fact that a large part of the book takes place in

So far it's been World War Z, hands down. The book lends itself to the audio format extremely well due to the fact that a large part of the book takes place in the form of interviews. The author (Max Brooks) plays the part of the interviewer. Another reason I love it is the cast. Alan Alda, Rob Reiner, Henry Rollins, Mark Hamill, John Tuturro among others make it a fantastic listen.