Interesting read from the Sloan Conference on trying to quantify shot quality. Very technical stuff and I'm still trying to wrap my head around it.
According to the data, Gerald Green is the best mid-range shooter in the game (Demar isn't mentioned in their top 5). Jose Calderon is the 2nd best overall, behind Kyle Korver. This isn't to say they are the best shooters, but rather they take the best shots and make them at a high rate.