I vote Ryobi in terms of quality/dollar. Often a 20volt Ryobi costs less than a 9.6volt Dewalt. And I don't care what circumstance - a 9.6volt Dewalt will never be more powerful than a Ryobi 20volt... Plus, Ryobi has innovative things like built-in level, drill bits, and a magnet to hold screws.
My 14.4volt Ryobi has even stirred morter - about 1 gallon for a minute (with proper pauses) without overheating
If I had money to blow, I would get Porter Cable or Millawakee. They both just feel so nice.