Well I never shot a Norinco, but they do have chrome bore which will hold up better in the long, long run than a non-chromed bore which the yugo has. The problem people are having is with the corrosive ammo that was used in them. My current Yugo is a shooter grade and has some slight pitting in the lands but still shoots 1 1/2 in at 100yds if I don't drink a pot of coffee before I go out. But since the Norinco was probably imported new and you're looking at an unissued Yugo, that won't be a problem unless you shoot corrosive stuff.
The other complaint that I have is weight. The Yugo has a bunch of stuff hanging off of the front of it which makes it kind of nose heavy in my opinion, the Norinco just has the bayo no grenade launcher and sight.
From a collector stand point, the Norinco is already rare, and the Yugos are all over, but in a few years the same will be true of the Yugo.
I can't say which is the better one, I would like one (or a few) of each. If the Norinco is in nice shape, and you don't feel like hassling with shipping and FFL paperwork right now, I'd go with it and never look back. You can always buy a Yugo later!