Theres a lot of good information in this thread. I want to chime in about an issue I have experienced that I dont see here. Chuck grip.Both in the hand while tightening, and of the tool afterward. I have used several drill makes; Porter Cable, DeWalt, Skil, Makita, Harbor Freight, Kawasaki, etc. Of these, and any I may have forgotten, the Makita stands out clearly as having the most friendly chuck. I have the Makita 6333D - - 14.4V and 1/2" Jacobs chuck. I bought it for the voltage-compatible with a tractor or car battery- and capacity to hold all popular sizes. Imagine my surprise to find a chuck you could grip so well that your hands turn into crossed box end wrenches. As the chuck gets tight the rotation turns into very small notching movements, seemingly aiding tightening and certainly inhibiting loosening in operation. The jaw grip on the tool is very good and easy to achieve. The only downside I ran into in Makitas application of this chuck was the keeper screw grossly limiting the insertion depth of the drillbit - an issue mainly with large bits. I ended up removing the screw - a metric lefthand shoulder screw. I planned to get one with a shorter shoulder, but Ive had no problem just leaving in out. This is a strong drill but not a hammer drill and wont loosen the chuck under its own power. If it does Ill deal with it.
Ive had the drill about five years. When a battery wears out Ill make an extension cord adapter to go to a vehicle battery.
Larry