Depends on usage, for job that require tons of screwing and torque--up to 20Nm, I use Bosch cordless Drill GSR120-LI. Proper powered tool that are durable/reliable.
If I need something smaller--up to 5Nm, Bosch GO is great.
If I need more control for delicate task, Wera screwdriver bit handle. My favorite is 838 RA-R M.
And for precision/micro.