The zipper of the resin zipper is the best, because the mold is fixed, the tooth shape does not change, so it will not escape chain.
Nylon zipper cheap, light, but also the most prone to problems, because the nylon monofilament instability, and sometimes there will be cracking situation.
Metal zipper texture is good, you can plating a variety of colors, tooth-shaped meshing depends on the quality of factory workers, mold can be adjusted.
In fact, these are not the problem, and ask you a dress to wear a few years ah? As long as your clothes are not the cheapest way to spread the goods, the quality of the zipper is still possible.