I think in general, if you're relying on disney transportation, the monorail resorts are better, because you're always an easy trip to the TTC, which is a great tranportation hub. You're also within walking distance of the MK, which is also a transportation hub. POR is more inconvenient to the hubs, which is negated somewhat by the fact that at MK opening and closing times, your "hubs" become unmanageable. Also, though, downtown disney is inferior as a hub, as compared to the MK and the TTC.
If you're planning on doing a fair amount of driving -- for example, if you have a car, it's better to drive to MGM whether staying at POR or the Contemporary -- then this is negated. But if you're relying on disney transportation, the CR is a far better spot.
After giving this a fair amount of thought, my view is that the best located resort, in general, is the poly, followed by the CR and GF. The poly gets the nod because you can walk to the TTC. For a trip heavily focused on Epcot and MGM and/or downtown disney, obviously you can't beat the boardwalk resorts -- and they have an awful lot to commend them too. But in general, assuming a 5 to 7 day trip with at least one or two visits to the MK, I'd say the monorail resorts get the nod with the poly first and the CR close behind.
Another thing is that when we go, we try to make disney transportation part of the experience -- going to the chip and dale sing along and then trying to time the boat ride back during fireworks, etc. Your options for this kind of highly retentive planning

are increased at the CR.