Sorry but the worst place in Chinatown for Chinese buns. They are the cheapest as far as I am aware, with the second being Mashion but the quality is not there. For normal buns Hong Kong Island is by far the best, for the rice balls with filling Mashion is better quality for a little more.
The "mochi" or rice balls have a pitiful amount of filling and the store overall just feels the most worn down and unkempt.