A 1/2" impact for sure, I bet I use my 1/4" air ratchet, 3/8" air ratchet, and 3/8" impact about equally, but when I need an air hammer or cut off tool I'm so glad to have them. I'd suggest the 1/2" impact, 3/8" air ratchet, and cut off tools first, but plan on buying the others because once you have them you'll find more uses for them.