Panasonic - not cheap though. I smash cordless drills/screwdrivers generally in under 12 months - they get a lot of work. The latest one I have is a Bosch and it is really good too. The last Panasonic lasted 13 months before the gear box packed it in. Makita are lucky to last 6 months.
Back in early '70's when I defended NATO against the Soviet hordes, battery powered tools were in their infancy and had not yet penetrateed the military (at least at our site in Germany). The sigmaintenance guys used a Yankee Screwdriver
to remove the screws holding the radio gear in the 19" racks:
I inherited my Grandfather's Yankee screwdriver but have never used it. By the time I was got out of the army, Makita was retailing battery drill/screwdrivers.
When it comes to buying tools is like buying a car, ford vs chevy. First thing I look on any portable tool, is battery life and most important battery price. Other important factors are weight, ergonomics of the handle, variable speeds. Here at work we have Milwaukee portable drills 28V.
I had a cheap Skil cordless drill that lasted for 11 years with the original battery. When I first bought it, I had to build a backyard metal shed (over 500 little screws). I guess I broke in the battery perfectly, because it could sit in my truck for months through wide temperature extremes and still hold a charge. When I tried to buy a new battery, of course they were obsolete and unavailable. I complained to Skil, who informed me of a recall on the charger, and sent me a $50 gift certificate for a new drill. The new drill was a piece of junk though. 3 months old, it fell off a 6' step-ladder and shattered.