Credentials: Grew up in a leather town in upstate NY. IIRC: Deer skin is supple and comfortable, good for jackets, dress gloves. Not strong. Pig skin is similar. Cowhide and horsehide are strong, but stiff. Goat skin-called cabretta- is a good blend of strength and flexibility, and is the best choice for rock star leather pants. Not a bad choice for gloves, either. In the early twentieth century, dogskin driving gloves were highly regarded for flexibility and breathability-not advocating, now, just sayin': don't be a hater.

Electric company linemen used to use cowhide gauntlets with wide, forearm covering cuffs, which were great for barbed wire projects. Cowhide welders gloves give an amazing amount of thermal and sharp edge protection, and are really cheap at harbor freight.

Leather is not a magic fabric: it degrades quickly with exposure to water and petroleum products. Canvas work gloves with leather palms have served me well for a long time, too.