Pennant Hills is about 15-20 km west of Parramatta, about 6 or 7 km from Blacktown. Really, I think they are better off putting a team in the Hills areas, where there are no clear cut lines on what people support, and a burgeoning economy of young families lives.
While I'd agree that the people of Pennant Hills would be more impressionable, I'd say Blacktown would be better for the image of the AFL. Rougher area. It doesn't really matter. All people in west Sydney would be targeted and ultimately the team would be aiming to play at Stadium Australia.