As far as the camera quality goes (i.e. ignoring the other issues like support and upgrading), my experience is that it's tough to make a good general statement. I've looked at the internals of 3 chinese market dahua models I have, and 3 international market dahua models I also have, and they sure look to me like they use the same components and have the same build quality. Wouldn't surprise me if they roll off the same assembly line. The difference I see is that the lower price chinese market cameras are just lower-end models, with small sensors and sometimes plastic cases. The lower end international models have these characteristics, too. I've not seen any chinese market starlights for sale on amazon/ali/ebay (regardless of what the seller is claiming). Performance depends a lot on individual models. I began my journey with some higher-end official USA rebranded hikvision cameras. The image quality was so bad I was on the verge of chucking the whole project. Out of desperation, I tried a chinese market dahua camera that was half the price of the hikvisions, and the image was stellar by comparison. Next I tried a chinese market hikvision camera with the same specs as the dahua camera, and its image was lousy. I'll stand up and say the chinese market 4431-series dahuas are good cameras, just as good as the starlights in terms of daylight image and build quality. At night, the starlights have a pretty good image advantage over them.
Andy sometimes stocks what look like international equivalents of the chinese market cameras. When he first had them it looked to me like the cost was about $10 to $15 more per camera vs. the chinese market equivalents. Well worth it, IMO, for the reliability and support of the seller, and that they should play well with a dahua nvr.