Reddit mentions of The Alloy of Law: A Mistborn Novel

Alloy of Law by Brandon Sanderson and read by Michael Kramer is the best audio book I have listened to. There is a character in it who is a master of disguise and changes his accents as part of his disguises - because of that audio book is great to listen to and adds another layer to the medium. It is part 4 of Mistborn series but you can even read it without before the first trilogy as it is set several hundred years after the events in it.

http://www.amazon.com/The-Alloy-Law-Mistborn-Novel/dp/B0064I1NAS

First Law series by Joe Abercombie were also books that I enjoyed listening to. They are a bit darker then your usual fantasy but characters in it are really great and I enjoyed it a lot.

Also, Discworld books by late Terry Pratchett and Vorkosigan saga by Lois McMaster Bujold are great as audio books as well.