It depends if you plan on constant use or not. It's a pain to wait for the pressure to build back up.
I use my air ratchet much more than I do my air impact. Snug it down, then break out the old torque wrench to finish tightening.
For non critical jobs, I have an antique Black and Decker electric impact with torque settings, at 10 pound (five pound actually) increments.
My criteria for buying a compressor is one that will start and run at 15 amps, 220 volt and I can (just) lift into the back of my truck. I tend towards, a larger compressors and slightly small tanks.
It's hard to get a compressor with enough watts, that can be used in a common outlet, that produces enough air to do everything (much of anything). Available fuses and the power supply is relevant.
I have two gasoline motor, powered compressors. The five horse will power anything I've ever wanted to do, the three horse I can lift myself.