Interested in environmental studies and how things look in China?
If so, I would not recommend Switzerland as place to pursue a degree. As this story makes clear, access to and friendly relations with China seem to more important to at least one Swiss university (St Gallen) than protecting the rights of students to conduct their research and complete their studies.
another reason not to do a PhD in Switzerland is the outrageous cost of living, especially if you’re a foreigner. but a good reason to do so is the excellent standard of govt support for research, such as at places like ETH Zurich.