OK, here goes on a whole bunch of subjectivity, based on day-hiking and/or weekending most of the 2.5 trails you mention, and on other information, but NOT representing any view of any organization I may be affiliated with.
Let's say one would be crossing the Potomac into Hancock, Md., where the two routes split. Hancock probably has adequate resupply opportunity, motel, a couple choices of modest restaurants, and a nice little bike shop but no outfitter.
....The east route heads out of Hancock on PATC's Tuscarora Trail. Camping is an immediate challenge on the towpath, roads, county park, roads, and PA Game Lands where treadway then adds to the challenge. See
http://www.trailjournals.com/entry.cfm?trailname=4974 ,
http://www.trailjournals.com/entry.cfm?trailname=6211 , and
http://www.trailjournals.com/entry.cfm?trailname=5400 for some passages through here. Pretty high up at the US 30 crossing but PATC moved the path 1/4 mile downhill from the summit bar.
North of US 30 east route enters State Forest with legal but dry camping, then Cowans Gap State Park, then follows a stream to near another PATC cabin. Head uphill now on Standing Stone Trail
http://www.hike-sst.org/highlights.htm ,
... -Would I, the WB reader, prefer to hike the GET or the A.T. across PA: Hike both and let us know!!