USMC
A few years ago, whilst on a trip to Fort Bragg, a grizzled CWO from 7th SFG told me that USMC pilots are considered the best at CAS by US Special Forces. He attributed their reputation for dependability to the fact that once a year every USMC pilot, wso etc. gets out their BDU's and re-aquaints themselves with basic infantry tactics attached to a 'grunt' unit.