I have a drawer full of air tools I never use any more. A quality electric impact is a lot more handy.
I'm seriously considering buying an electric impact (Dewalt) over an air tank next time I have a large project to work on. The air tank I have now is getting pretty tired and is quite small for air powered tools. That being said, we've used it for nail guns, die grinders, cut off tools, paint guns, etc. While it works, if I ever really get into air tools, I'm going to look into a big purchase for an air tank and plumb drops around the garage. Until then, I think I'm going electric.