I've actually researched this quite a bit and am deciding between those 2 too (and USC for other reasons)...you're right about recruiting at Gtown...pretty much every major bank recruits there for i-banking. They seem to have a strong undergrad pipeline to NYC, so the banks show up for the UGs and figure they might as well take a few MBA's...
UNC has stronger ties to Charlotte banking but also places pretty well in NYC. Paul Parker (the head of global M&A at Barclays) is a UNC guy and takes a ton of MBA's every year. And the proximity to Duke helps (banks come for Duke, check out UNC too).
These banks recruit at Gtown: JP Morgan, Citi, BA/ML, Wells Fargo, Nomura, BMO, Lazard (Barclays, DB, CS, Goldman, UBS recruit but not on-campus)...
The UNC list: Barclays, Wells Fargo, BA/ML, MS, Suntrust, UBS, Jeffries...
I would ignore the rankings...in terms of i-banking/corporate finance, they're essentially peer schools.
Hope that helps...good luck with your decision...