Well, I usually agree with Chris (Falcon67) but have to disagree on this. Go bigger if you can. I HATE sitting there WAITING on a compressor to catch up.
DA sanders take a lot of cfm. You didn't say anything about sandblasting parts, but that also takes huge cfm.
Anyway, I know you posted that "around here" they want new prices for used. If you are not in a huge hurry, keep looking. I found a Dayton 2 stage 5hp 80 gallon compressor for $275. It was cheap because of the 3 phase motor (most residences don't have 3 phase). I bought a brand new single phase motor for $300. Sold the 3 phase motor for $100. There are deals out there if you are patient.
Ironically, we are moving to a new property that has 3 phase.
As to this: "Central Pneumatic is 15.8 CFM @ 90 PSI, Quincy is 12.8 CFM @ 90 PSI, but witch compressor is a better compressor?" I am sure the consensus around here is that the Quincy is the better built unit. But as underpowered as it is for what you want, I don't believe you would be happy with it. What difference does it make if it is the better built machine if it doesn't fit your needs? My limited experience with Central Pneumatic is that it is 2nd rate at best. There is a reason they chose initials that are the same as the old Chicago Pneumatic.