mphc

I'm also trying to decide between those two! My undergrad was in biology so I was leaning towards Guelph because their zoonotic disease elective sounded really interesting and I had a friend who went to Guelph for their mph and said that having the Ontario Vet affiliation was a really interesting side of their mph degree with the course. I only like Queen's because it's my alma mater which I guess isn't the best reason but whatever works for you! 

Also, if you're deciding between something else and Guelph, lots of schools have the potential to let you take other mph school electives which was something I was looking into if I didn't choose Guelph. Except most schools only let you during the practicum summer, the zoonotic course at Guelph doesn't run during the summer. So if you had any other electives in mind that do run during the summer, that's always a plus! 
Good luck with your decision!

Congratulations on getting in! I don't mean to hate on Queen's, I actually love it here in Kingston because I love small towns but I find that there isn't a lot of support on campus academic/mental health wise. In my personal experience, I found that the academic advisors didn't provide a lot of advising and I felt more judgement than anything and the mental health resources here take a good amount of time to even speak with a professional. I'm pretty sure that graduate students have their own version of academic advisors but I don't expect them to be very different. Not that these are huge reasons but I have heard some great things about Guelph from my boss (I also work for Queen's currently) and another PhD student who did her undergrad at Queen's then masters at Guelph then PhD at Queen's (she chose to come back to Queen's because of the amount of funding they wanted to provide her for her research). I figured it would be a great time for some change!
(Also, if I were to get the same caliber of academic rigour at either of these institutions, I'd prefer to stay away from the reputation that Queen's has amassed over the past few years. I was at Queen's for the horrid horse slapping, the racist party, and the coronavirus party which honestly wasn't the best look for Queen's.)
All the best with your decision making!