Just wanted to write a quick post about my two favorite screwdrivers. We have two Snap-On screwdrivers at work, (both are ni-cad not Lithium batteries), four 18v Makitas, one 18v Dewalt Nicad, one 12v Dewalt Nicad, and two 12v Li-ion Dewalt. The bigger 18v drills are just WAY overkill for an A&P. They are too bulky, and the added power just isn't really worth the weight. It will kill you to take panels off the underside of a wing with those 18v drills over your head. The 12v Dewalt Nicad is only about six months old, and the battery life on it is pretty pathetic. That makes it pretty much a two horse race between the Dewalt and the Snap-On.
The Snap-On lists for $143, and I paid $200 for the Dewalt drill, screwdriver, and impact driver, plus the charger and three batteries (killer sale!) from Lowes. I don't think that you will go wrong either way, but each has advantages. The Snap-On is a little pricey for what you get, but it is very compact (important especially for avionics guys), and the adjustable torque clutch works really well. My dewalt one has 15 torque settings, and it seems like I have to adjust the torque five times a day. The Dewalt really struggles to get a consistent torque on locking nutplates especially. I've never tried a Li-on Snap-On driver, but the Dewalt's batteries seem to last forever, even on heavy inspections. I probably charge my driver every other day, and the Snap-On seems to need at least once a day. The impact driver is fantastic for removing tough screws, and the clutch on the drill seems to do pretty well. The lights surrounding the drill, screwdriver, and impact are tremendously helpful in the aviation field. I find myself using the screwdriver as a flashlight pretty consistently. I definitely think it is the winner in the bang for buck category. I would highly recommend either, but for my money, Dewalt is the way to go.