Norinco hands down. It's made of better steel. In fact it's made of better steel than Colt's are. Colt's are made from 4140 ordnance steel and Norincos are made with 5100 tool steel. Armscor are cast steel. Not that there's anything wrong with cast and the Armscor's are good guns but if you have a choice go with Norinco. BTW the mags for both are junk.
As a machinist and a Colt owner I'm very curious as to where you get your facts, I'm not trying to be a jerk here, so please forgive me, but there are a lot of ol' wives tales on the internet about Norinco quality and I have to laugh quite often at what people believe about these guns.
People throw around numbers and claim that these guns are not only as good but superior to American examples.
As someone who has machined tool steels imported from all over the world and heat treated them for industrial puposes I can tell you Chinese made tool steels are not what they CLAIM to be, the M-14 reciever copies were such a disaster they were a complete failure before the import ban.
That having been said, I would agree with you that A norinco would probably be a better choice than an armscor, I've seen metal quality and machining from armscor that make pot metal cap guns look good.