Ingersoll Rand is the one for me. We have had HF and they are OK but for production work on big Trucks it turns out IR is the best.
We have had great luck with the "professional series" from Harbor Freight Tools. One-half to one-third the price of I-R and C-P models. Check them out on the net! There are basiclly two types of actions, single and double hammers. The key to longevity of any air tool is a clean air supply and keeping it oiled.
I pretty much quit using those whimpy air guns and went hydraulic. Purchased both a 1 in. drive and 3/4 in drive used on ebay in the range of money your talking. 2,500 ft-lbs continuous and no bog on the big one......plugs into tractor hydraulics so you have portable power. Brand is Stanley Hydraulics. They are big bucks new.