I don't know anything about UNC, but... here's my two cents on the MGH and UTA:
MGH is geared towards those of us who want to work in medical settings and with adults. UTA is geared towards working in school settings and especially bilingual school settings. That said, you can technically work in either setting after licensure, but the question becomes, how easy will it be to get a job in X setting, and how prepared will I feel?
I got in to MGH and UTA last week, too. I'm struggling with the idea of massive debt after grad school, and wondering whether I will be able to work in my dream setting after school. I really want to work with aphasia and other cognitive language problems, and I want to work with adults... but I'm not sure if taking out $80K in loans to go to MGH is a financially sound idea.