Quick way to consider air compressors:
The tank is the battery. A 60 gallon tank holds twice the air as a 30 gallon.
Tank pressure is the voltage. A 150 psi tank holds more air then the same sized one at 100 psi.
The pump/motor is the charger. The more real HP, the faster the tank gets refilled.
Note that the hard equation is 1 HP = 750 watts assuming 100% efficiency on the motor. A lot of stores will advertise 'Peak HP' in excess of 5HP on a 120V compressor. Peak HP is mostly meaningless for a compressor. It doesn't really matter if the motor generates 6HP for that fraction of a second it is starting to spin up. What matters is the running HP. Be wary of any compressor claiming over 2HP on a 120V plug. 2HP = 1500 watts which is close to the max rating for most 120V outlets. Plus most motors are not 100% efficient.
CFM. Be sure to compare the CFM at the pressure your tool wants. Some low end compressors will list a decent CFM number at 40psi and a much smaller number at 90psi. Most tools want 90psi and most paint guns want 40psi.
A decent rule of thumb is 4CFM @ 100psi per HP.
https://www.quincycompressor.com/air...r-horse-power/
Avoid the 'oil less' compressors. They tend to be under performing and overly noisy.