There's a new book by Jennifer McLagan, "Fat: An Appreciation of a Misunderstood Ingredient, With Recipes" - available from Amazon.
I've not read the book.
The chapter on pork fat is entitled, "pork fat: The King". In America, Mangalitsa, finished in the best possible way, provides the king of pork fats.
Mangalitsa Sow's Loin
Of the various animals whose fat we consume, pork is special due to the amazing control that we have over the fat quality. By raising special breeds of hogs (lard-type hogs) in special ways, we can produce some of the world's best fat. This is better understood in Europe than in the USA.