A black Latigo sling and a tan English Bridle sling were both soaked in water for several minutes then placed into a freezer for over 24 hours.
During the soak, the Bridle leather seemed to absorb more water while the Latigo seemed to resist absorption and tried to shed the water off.
After another 24 hours when both slings were thawed out and fully dried, there was hardly any evidence that either sling was frozen.
Both types of leather are made for outdoor use and both did their job exceptionally well during this test.
If necessary to choose a tiebreaker, the Latigo Leather would be the winner for its water repellency and overall durability.