I listen to audio books on my (long) commute, and lots of the top ones have already been mentioned.
But let me give a shout out to the "Iron age" trilogy written by Angus Watson, and narrated by Sean Barrett. Not only are the books really entertaining, but Sean Barrett's narration is really good and he even does Scottish accents well (a rare talent).
The books are set in iron age Britain and cover an under explored setting for "fantasy" books.
Anyway check them out, the first one is called "Age of Iron".
In different genre altogether is another audio book I'd recommend, which is "The Wicked Girls" by Alex Marwood narrated by Anna Bentinck . This is contemporary novel about two ex-criminals (very obtuse description there). Best to go into this one as unspoiled as possible.