Choosing between primary advisors for a PhD program
This paper asks about postdocs, but I suspect the conclusions would be the same:
https://f1000research.com/articles/6-1642/v2

After surveying Postdocs, they find that the only singificant predictor of life satisfaction is having how collegial atmosphere in the lab is.  

Thus I'd say pick the supervisor who's group you feel most at home in. Your PhD will inevitably suck at many times, and the only people who will really understand what you are going through are those in your group. Make sure they are people you can trust and who will be there for you.