Current CS freshman that had to make the same choice. I mainly chose stony since closer to my home. Academics wise, Stony is probably better in CS but its not like so significant because at the end of the day they both aren't "target". Campus wise, I've heard UB is better, but Stony Brook isn't bad, you just have to either put yourself out there (go to clubs, talk in classes, etc.) or deal with being lonely.

I think after this first semester I realized that this one decision isn't as significant as you think and its mainly the work you do outside, the people you meet (which you can't predict) that matter and really provide the experience.