I am a mainland Chinese working in Hong Kong. I used Futu before and thought the interface was good, but the commission fees were too expensive in the long run. A friend recommended BOOM to me. It has an old-fashioned Hong Kong-style interface, and I wasn't used to it at first. But after getting used to it, it's okay for trading. The main advantage is that the commission fees are cheaper than others. Sometimes I trade Japanese stocks. I heard that they can trade stocks in 16 popular markets.