I used 18-volt and 20-Volt Dewalt drivers and drills at work and home. The 20-volt set (4-pack) includes Lithium Ion batteries, and I have been replacing the 18-volt ones with the same type of batteries. A couple of years ago I bought a 12-volt Dewalt set like this:
http://www.amazon.com/DEWALT-DCK211S...%2Fdriving+set
I used this kit for small to medium jobs, primarily at home. Used the driver to drive the special screws used for DuRock, right into the shower studs through 1/2" BackerBoard. And I am not talking about new studs that are nice and easy to drive screws into, but seasoned studs on an old house. Don't let the small size of batteries in this kit deceive you into thinking they won't last or have enough power. The driver and drill produce quite a lot of torque, and the batteries last, and last...
In my view the older Ni-Cad batteries, regardless of brand, are as good as trash compared to Lithium Ion batteries such as the ones on the kit above.
Makita and Dewalt are the way to go.