I had terrible trouble with Quicksets in my first year of pumping. They would frequently fail, every couple of weeks at one point. Complete nightmare, with rampant BGs out of nowhere, which then settled down as soon as a new set was put in. Nearly made me give up on pumps altogether.
Many of them would kink after they had been inserted, so the insulin didn't get through properly. They would come out with the cannula bent at 90-degrees half way up (can't be like this on insertion because the needle goes through).
Angled sets don't seem to get squashed in the same way. I've had almost no failures since I switched to angled.