Der Ring des Nibelungen by Wagner and a close second third would obviously be Loreena Mckennitt The Book of Secrets as well as Mediaeval Babes.
But in reality I cannot choose as my music list is endless and it would certainly not be fair to place one above the other as something as complex as this matter is not comparatively possible given the circumstance at hand.
If I were on a desert island as opposed to a deserted Island, I would probably long after George Frideric Handel, Water Music hoping to lessen the misery of a parched throat.