Which is better, canvas apron or cotton apron?

That depends on your purpose. If it is used for welding or other workplaces with sparks, use a cotton apron, which is resistant to high temperature and will not deform. If it is not used in high temperature places, use canvas apron, which is wear-resistant and dirt-resistant; If it is a waterproof canvas apron, it can also be waterproof and oil-proof!