I agree with Tufnel. It really depends on your future plan.
I was fortunate enough to attend colleges at both places (Hong Kong and US) - I like both of places but realize that they hold quite distinct strength. I assume you are from China - that being said, if you aim to have a teaching job in China, a PhD from a Hong Kong university, esp. HKU and CUHK, which I attended, will not hurt because they are both very good at Chinese and East Asian studies. The public policy subfield is particularly strong. If you really want to come to the US, you can also do your MPhil in Hong Kong and then apply again with a solid research thesis, which can serve as a good writing sample.
For NYU, I am not really sure to how much degree it will help you with your future application. They take a lot of MA students each year and you will not be able to work with the main faculty body in the Department. Most MA instructors are adjunct - I am not saying it is bad, but for me I feel the program is better for those who focus on professional careers. But please bear in mind some people do end up being at very good PhD programs - esp. those who become very strong quantitative savvy. Another thing is if your subfield is IR, NYU may not be a bad place. One of my PhD classmates was from there after having worked at Foreign Affairs for a couple of years.
For Tufnel, no offense - but I believe the proper phrase is actually 教书 instead of 教授. So in Chinese I will say 等你念完取得學位時, 想在哪裡教書?