Definitely QBZ. We've been evaluating various lifejackets on the Clipper RTW race, and whilst a year of full time use is a little over intense, the results are worth noting.
On anything velcro inevitably over time the velcro fills up with lint etc, and despite best efforts eventually wears out - this was most noticeable around the back/hood area where there was most articulation. We have our crews regularly check their lifejackets with inflation tests which won't have helped, but they started looking shabby after about the 4th race (15 races making up the RTW voyage).
By contrast, the new zipped ones we have are much better.