Disclaimer: I'm on Penn's waitlist, so please please please go to UNC 😀
Seriously though, while UNC is a great school and certainly won't close any doors for you, Penn has a greater weight in academic medicine. Plus, Penn has one of the highest median Step 1 score and its students match to top *academic* residencies. Penn's curriculum allows enough flexibility and customizability for you to prepare your best residency application possible, whether you're interested in an ultracompetitive specialty or a research powerhouse. Can you go to a great residency from UNC? Absolutely! But you may have to be more self-motivated, while Penn students pretty much uniformly match to top residencies, which means that whatever Penn is doing to its students, it's working. Also, consider the "regional bias" in residency application (yes, at least part of the reason why a lot of students stay in the same area after medical school is because they want to, but it's quite understandable that PDs may have a slight preference for "locals" simply because they know local schools better and because local applicants have a better incentive to stay in the area): since you have roots in NC, it may be easier for you to return there for residency even if you go to a school in a different region; however, if you stay in the same region for a long time, it may be a bit more difficult to convince adcoms that you want to move to a different region, should you decide to apply to residencies outside of your region.
As others have already said, wait for fin aid to come out (Penn has a lot of money to give and may pleasantly surprise you) and attend both second looks if you can. Ultimately, I believe that fit matters a lot, so I personally wouldn't want to go to a school I would be miserable at even if it was a more practical choice; take another look at each school and at your potential classmates and see if you feel any different about the schools.
Bottom line: I cast my vote for Penn, unless you feel you'll be miserable there.