Leather
I use English bridle leather for all of my handmade leather belts. I use bridle leather from JE Sedgwick. This is a full grain leather that is cut from the butt of the cow's hide. This is the strongest and best part of a hide.
Be careful when comparing leathers as real leather can mean many things. Anything from a 0.1mm thick piece of leather over cardboard to a glued together mess of leather off-cuts. Anything that says cut to length will be a rubbish piece of leather. The average person would struggle to cut some of my bridle leather with your everyday items!