Basically, electric impact wrenches are easier to use. The great thing about an electric air compressor is that you do not require an air compressor to run that one and put the cord or recharge the battery to make the electric wrench ready for work. In automotive shops almost all types of impact wrench are available they use on the basis of requirement.  If you need an impact wrench for smaller works, or you own an auto repair shop then an electric impact wrench is probably a good and worthy option for you to go at a low and affordable price.