Lithium ion vs Air

I have both. I can't imagine being able to do relatively fast and easy work without either of them.

For cordless, all you really need is a decent impact driver and drill, IMHO. If you shop around, you can get a decent set for little cash. I currently have a Ridgid impact driver and drill combo that I've been using for 3 or so years without a hiccup. I think I paid about $150 for it, on sale.