I had to switch to full zip jerseys in summer 2018 while recovering from a broken and dislocated shoulder. I was concerned about zipper quality but, so far, so good with decent mid-grade quality jerseys from Pearl Izumi (two short sleeve, two long sleeve), Garneau and Bontrager. Pearl Izumi zippers were a bit better integrated into their aero jerseys, but all of 'em seem good enough.

I already had a couple of entry level Garneau jerseys with 1/3-length zippers and they economized there, but those zippers have been fine for five years now. Ditto a low priced "Koramon" no-name jersey from Amazon. Lower cost zipper but it's been fine for three years of regular use.

Most full length zippers on sports wear have finicky entry/ending points (the bottom stops or retainer boxes) where the slider mates the two halves with teeth. I try to be patient zipping and unzipping to avoid damage there.

The worst zippers are usually on bags -- any sort of carrying bag, from camera to laptop and other gear bags. If a low cost bag seems to use good material and seems sturdy but the cost seems improbable for the apparent quality, check the zippers and stitching. That's where the knockoffs, counterfeits and bargain bags will pinch pennies. The first thing to fail on my otherwise decent weatherproof AGU bag (made in Holland) was the zipper on one of the side pouches. I'm guessing they're trying to compete with Ortleib and pinched pennies on zippers. The main closure for the lid is hinged with bungee strap closures, and those have worked fine for several years. But the side pouches are useless because of the zippers. In contrast a Kirtland Tour Pack handlebar bag I bought in the 1970s was still going strong after 30+ years and served hard duty in a second life as a camera gadget bag and utility bag for my safety testing equipment on the job. Some stitched loops failed after several years but the zippers all held up well.