I use Scientific Angler GPX double taper 3 and 4 weights. I think SA makes the best fly lines on the market. They shoot well, roll cast well, and last a long time. I would recommend their XPS lines also. Buy the double taper lines. When one end "wears" out, you can reverse the line. Double tapers are also superior for roll casting, which you will find yourself doing alot on PA streams. SA lines cost a little more, but you get what you pay for. Try eBay and shop on the net for bargains: you'll have a long winter to look. All just my experience and opinion, of course. Hope this helps.
John