For a traditional and sturdy halter that is functional and looks great, leather is an excellent choice.
Things to Consider:
Stitching -- Look for good, solid stitching on your halter that will withstand wear, weather, and years of use.
Oil/Polish -- To help preserve your leather halter for years and keep it smooth and pliable, a leather oil or polish can be used to treat it when necessary.
Durability -- Leather is a great material for durability and style. It is a look that never goes out of style and can be found in a variety of patterns.