I just visited these two schools and find myself facing a difficult choice.
Princeton is more prestigious, but there are only a few choices of potential advisor due to the small department. The prospective advisor (Haw Yang, http://www.princeton.edu/~yanglab/) is strict, and it takes 6 years for his student to graduate.
Madison has a stronger chemistry department, with 7-8 faculties conducting spectroscopic research (which is my interest). The atmosphere of the department is relaxed and active, I feel that people are more friendly there. Prospective advisors are Martin Zanni (zanni.chem.wisc.edu) and Randall Goldsmith (goldsmith.chem.wisc.edu/).
I would like to work in a supportive environment, but professors from my undergraduate institute told me that my best option is to attend the most prestigious university in order to find an academic job (in China) .
I would appreciate it if you could give me some advice.