There are several factors involved with choosing a piston type of air compressor including whether it is a single or two stage. It also can make a difference on how big a tank you have. A single stage compressor puts out a higher volume of air but at a lower pressure. The advantage of a 2 stage is that it takes longer to unload the tank before the compressor has to start again. You are never going to regret getting more CFM or PSI. You will regret not getting enough. If ever you get a sandblaster you want as much air as possible at a higher pressure. Cheaper suction types need to operate at at least 80 PSI so you start at the limit if using a single stage. So obviously a two stage works better for sandblasting.

I have 2 Quincy 5hp two stage compressors. I only run one when I am painting (I can use both when sandblasting). With an 80 gal tank I can usually do a entire coat of paint on 1 frame when the tank is starting at 175 PSI before I run out of enough air (in other words until the tank gets down to having 25 PSI). You will remember that I use paint guns with 1.3 or bigger nozzles too. Don't forget to get Hi-flow connectors. I like aluminum ones (available at Home Depot and many other places).