Hm, Do you have enough saved up to go and visit each place for a few days? Have you been to either yet?
I've always found that getting a feel for a place is always the best in helping me make my decisions. Sure, you've spoken to them, but can you "see" yourself living in either place? 3 years is a long time to live somewhere, especially if you're unhappy.
You can logically weigh the options/make a pro's & con's list, but what is your heart saying?
I definitely understand what you mean by starting on your career, as doing a PhD is the highest level of education you can obtain--and you'd be considered an expert in that field. So, I guess something to consider in that respect is-- does one option keep open more doors for you?
For example--In choosing my undergrad major, I was having trouble deciding between Exercise&Sport Science, Nutrition, Biology, Chemistry, Psychology(Neuroscience). I ended up picking Biochemistry, because I could still quite easily switch into a career in plain old Chemistry / Nutrition/ ESS/ Neuroscience. My first two jobs out of college were in biology. The second was perfect. I worked with chemicals to see how they affected receptors in the brain--so it combined the chemistry, cell biology, and neuro sides of things.
Would you be able to do your thesis for Public Health in something that still allowed interaction with the Sport Science side of things??, or a thesis in Sport Science that tied in well with Public Health? I think combining the two would help prevent you from feeling like you're abandoning sports health, and help you make the right choice
Sorry I'm not more help, but it's ultimately your decision. Best of luck!