Milwaukee M18 Lithium Ion. Hands down. Unbelievable power and great battery life if properly maintained.
I have the hammer drill, impact driver, light, sawzall, 4 1/2" angle grinder. Soon to be adding the 6 1/2" circular saw and the 2663-20 18-Volt M18 1/2-Inch High Torque Impact Wrench with...