If you want to give blood in Hong Kong, this center in Central is one of the best places to do it. Mainly because it is one of the least crowded. I have given blood many times there and I have never had to wait for more than a few minutes.
In contrast, I had to wait for more than one hour at the center in Mongkok both times I gave blood there. And I heard that it is also quite busy at the center in Causeway Bay. The one in Shatin is OK but it is a bit far away.
Central is the core business district, where there is a high concentration of business people, civil servants, and people in suits with well-paid jobs. In contrast, there appears to be more young people and blue collar workers in Mongkok. I do not wish to jump to conclusions. But the relative crowdedness of the centers seems to say something about who are the more likely blood donors in Hong Kong. In fact, I do not remember seeing anyone in suits in any of the blood centers.
To give blood, you have to pay a real but small price - being a bit uncomfortable for a little while (10 minutes is about all it takes). You give up one-tenth of the blood in your body but you will recover quick enough and there are no lasting effects. I have given more than 40 times in the USA, Canada and HK and it didn’t seem to have done me any harm. But you will feel great afterwards for being able to help someone - for whom it may be a matter of life and death.