I am assuming you are in New Zealand and you are asking if you should stay at the University of Auckland, go to Tsinghua, or go to America. I am also assuming you want to study law. There are a few factors you want to consider in making your choice:

1. Where do you want to ultimately work and live (you should go to the country you want to ultimately work in)
2. What kind of starting salary you want (American has the highest starting salary, and China has the lowest for a lawyer)
3. How many years of schooling would you prefer (America is the longest, China and NZ similar)
4. What kind of education do you want (America provides a liberal arts degree where you study a lot of different things, China and NZ have professional degrees at an undergraduate level)

Law school in China is usually at an undergraduate level and it is taught in Chinese. However, for Tsinghua, they do have a Masters of Laws program, which is taught in English and specially for foreign students.