Which air compressor is better?

Its not the gal or Hp

its the CFM,

Cubic ,Feet per minuit

look at your air tools and see what CFM they take at what pressure

The short answer is the 20 gallon is probably better.

But the main thing you need to look at is CFM (Cubic Feet per Minute) which is the measure of air flow an air compressor can provide. For a good explanation of what to look for in a compressor and how much CFM certain air tools require check out this link: http://www.best-air-compressors.com/air-compressor...

You need to look at the output of the compressors in CFM. This is always provided on the compressor. Than weigh that against what you plan on doing with the compressor. Air tools generally are high CFM users. Trying to use a compressor that is too small is frustrating and also hard on the compressor. A compressor that has a higher output than you need is always better than one that is too low. So, bottom line is to determine what you plan on doing with it and match the cfm to that. Also a larger tank is a plus.

My air impact wrench won't run at 125 psi. I have 2 air compressors now. I like tools so no boggyeal to me. Better to have it and not use it, then need it and not have it.