Enough of the this plane is better than that plane. It much more interesting, IMO, to know how solid the market is for used aircraft; FedEx has been a part of this market for some time. Indeed, it surprises me just how few aircraft UA has in storage. From their 10K:

United and Continental operated 354 and 348 mainline aircraft, respectively. The regional fleet is comprised of 275 aircraft at United and 276 at Continental. In addition to the aircraft operating in scheduled service presented in the tables above, United and Continental own or lease the following aircraft listed below as of December 31, 2012:

Two owned Boeing 747-400, including one operating in charter service and one in storage;
One owned Boeing 787-8, which has been inducted into scheduled service subsequent to December 31, 2012;
One leased Boeing 767-200, which is being subleased to another airline;
Three Airbus A330, which are subleased to another airline;
Two leased Boeing 737-300 in storage;
One leased Boeing 737-500, which has been returned to the lessor subsequent to December 31, 2012; and
23 leased ERJ-135 in storage

Apart from the ERJ-135s, that is not many parked planes at all.

Judging from the empty space I've seen during recent visits AVW, GYR, MHV, and VCV I suspect that UA isn't the only one finding buyers for their planes. I only hope that most of these buyers are operators - like FedEx here - rather than chop shops. Anyone recently been to IGM, ROW, ABI, or ASP and able to comment on the parking lots there?