Congratulations on being admitted!
I totally agree. You will spend 5 years working in a lab with that professor. So, you have to pick the professor and the lab not the university. Pick the the research group you are more passionate to work with. Even if you will reject the best program in the world.
If you are interested in both or if your interest in both is nearly equal, you can decide based on other factors, like the program ranking, the city you would like to live in, etc.
Wish you all the best.
Shehab