If I'm not mistaken, a relatively recent issue of Consumer Reports indulged themselves in this. Though I don't know specifically if they talked about the architectural shingles, they should have info on the mfgrs..
Best to ya. Perhaps others can help. Perhaps you can go to a Roofing Equip & Supply House (see Yellow Pages) and pose the question as if you're interested in the architectural shingles from them and ask them to price them for you AND tell you the qualitative differences.