In a commercial environment (and with race teams at the track), the air impact wrench is still preferred because of the consistent power delivery. There are no concerns about a battery running flat when you need it most. For hobbyists or home mechanics, it's very much a matter of personal choice. Cordless impact wrenches don't need a compressor and hose, so they're more portable, and it may not matter if you have to wait a couple hours for the tool to charge. However, good cordless wrenches can be twice the price (or more) of air tools.