If you are a graduate student of Central South University, occupying an area is actually an advantage. You can have a good relationship with the leaders of colleges and schools, which should be beneficial to stay in school and teach in the future.
If you go to Harbin Institute of Technology for graduate study, Zhongnan is not bad in mechanical strength, but the overall strength of Harbin Institute of Technology is still top-notch. If you don't stay to teach, it will be your best choice. Master students majoring in mechanical engineering in Harbin Institute of Technology are still very popular every year, but if they go back to Central South to teach, they will have a strong professional advantage, but the help they have accumulated before may not be great.
Just some personal opinions, I don't know if it will help you.