Although the subject is very prosaic, zipper quality can be of interest to sailors. We usually have been ordering from the US via eBay. It is the socalled Injection Molded type.
The #10YKK is a solid size that we use with canvas. They come in fixed lengths, and unfortunately we could find none for our 5meter+ lazybag project when we did it. But a domestic sailmaker company assured us that the coil zippers were just as good and durable. They can be installed at any length, so we ordered that type.
It has been 5 years, but I expect a canvas zipper to last more than that without wearing out. Ours is starting to come apart. As can be seen on the picture, the coils on the coil zippers are sewn in place. This makes up the structure of the zipper, as opposed to the other more solid type. That solution is vulnerable to wear, as the treads will start to unravel if they are cut at a point. I would expect the zipper to disintegrate with continued use. It will need to be hand sewn for repair.
I would recommend the Injection Molded type wherever it can be used.
