Hello, I know this has been brought up a lot and believe me I have read all the threads about them! I'm looking to buy a compressor for our bodyshop. It's going to be for the paint booth. I have narrowed down my choice to either a Quincy or champion. They are both 7.5 hp with there max packages including after coolers, automatic drains, low oil protection. Any info on which one to buy will be greatly appreciated.
http://m.northerntool.com/products/shop~tools~product_200350477_200350477?hotline=false
http://www.tptools.com/Champion-75HP-2-Stage-80-Gal-Air-Compressor,805.html
Well, did you pull the trigger yet? I'm a bit of a 'compressor geek' and in our shop, I run a Quincy QR 325 (disc valve) driven by a 5HP Baldor, sitting on a 120 gal, Vertical tank with a 240 gal. reserve next to it. I added an inlet silencer on the pump and you can truthfully carry on a conversation

standing next to it while it's running. Bottom line is that the Quincy QR series are built to run 7-24...but they are also the most costly pumps around. Quincy also has a line of QT (reed valve)pumps that are pressure lubricated, as does Champion and Saylor-Beall. As usual, you get what you pay for.
As far as quiet, of course the slower a pump turns, the less noise it will produce, so if noise is an issue, buy a larger displacement pump driven at it's slowest RPM. Personally, I'd go with the Quincy QR series first, followed by Champion PL (pressure lubricated) R-series, then Saylor-Beall's pressure lubricated line of pumps. All 3 use centrifugal unloaders in their higher end pumps. Any choice of the 3 will serve you well. Motor choice...Baldor.
Good luck, and keep us in the loop!
Tom