[Dave S.]

For most air tools you can get away with cheap tools that will work pretty well. That includes air chisels, die grinders, speed wrenches, grease guns, etc. But spend the money for a decent 1/2 inch impact wrench. I think mine claimed to have close to 700 lb-ft of torque and it is barely enough for many jobs.

The compressor it's paired with isn't nearly as important as the quality of the impact wrench, because you usually only use them for a few seconds at a time and the compressor can re-charge and recover. Now if you regularly use a die grinder or air drill that use high volumes of air and typically runs continuously for much longer intervals a better compressor with higher CFM would be helpful.