For a shop compressor that will see quite a bit of use I would recommend a unit with a belt driven, cast iron compressor, 60 gal tank, minimum 10cfm @ 90psi. I would not recommend a direct drive,
oil less compressor as they are generally much noisier and have a shorter life expectancy. Quincy, Ingersoll-Rand, Kelloog, DeVilbiss and Campbell Hausfeld are all good brands.
Ted