UPMC is obviously much more prestigious, takes five residents per year, is busier, offers internal fellowships in neurophysiology and stroke, has an neurointerventional program friendly towards neurologists, and opens many fellowship doors.
AGH is usually underrated. They're very busy, too, but not as much as UPMC, take four residents per year, offer internal fellowships in neurophysiology and stroke, do not have an interventional program friendly to neurologists (run by radiology and favors rads and NSG), and opens many fellowship doors, but less than UPMC.
UPMC offers more research opportunity, too.
I think that if Pittsburgh were a coastal or more cosmopolitan city, then the AGH program would be much more competitive.