There are so many good whites (Chenin Blanc, primarily) and reds (esp. syrah) from South Africa that it is hard to know where to start. I suggest doing some research on reviews, ratings, etc., then come back here with some ideas to discuss and get feedback. I'm sure others will chime in with their favorite producers. Many of better ones I have had there are not available in the US and are very inexpensive by our standards.
As for China, I have had a few (Great Wall, Chengdu, and one from Henan Province whose name escapes me at the moment). None have been memorable; however, which some French, US, and Australian consultants in China, things are looking up. But for now, I would buy only as a novelty, not to drink.