It's a tough choice to make. Out of the courses I've played, there is a group that stands out to me, they include Huntingdon Valley, Rolling Green, Philly CC, Indian Creek, Lancaster CC, Lehigh CC & Manufacturer's.
If I had to pick one, I would say Huntingdon Valley CC. It has a tremendous variety of holes, and with the topgraphy and routing, you are asked to hit shots from every conceivable lie/stance. Another reason I would choose HVCC is due to the conditioning and setup of the course on a day to day basis. The Supt. Scott Anderson and the club in general promote firm & fast conditions. I can't think of another club in the Phila area that maintains this type of play on a more consistent basis.