If you don't have an academic preference for one program over the other, and if the money they offer is the same, then I'd go with Harvard. I think Boston is a better city than Chicago. Also, while UChicago has a stellar reputation, it doesn't have the same name recognition as Harvard, especially internationally. I know that these are superficial factors, but if you can't decide based on substance or financial aid, then there's not much else left to judge. That being said, I am no expert in your intended field of study, so there may in fact be significant differences between programs in terms of academic strength, job placement, etc.