servos make too much noise
so then I can choose between a stepper or a dc motor with an encoder.
with a stepper I'll need a driver that can do micro stepping.
is a dc motor with an encoder as accurate? easy to code for?
Try the Lego EV3 Large Servo Motor. It uses I2C rather than the Servo library. It is very smooth and relatively quiet. Years ago, I used them to make a mannequin head that nodded realistically if it heard the timbre of my boss's voice (it's unique) and shook it's head when any other voice was heard.
If power is not an issue (using wall power), a stepper is the easiest.
If using batteries, motor with encoder: more work to program but more power efficient.
Do note that in both cases you need to be able to zero your motor, so you need a limit switch of sorts, to allow the system to find where the head is on startup. A servo has absolute encoding so doesn't need this.
Also I bet there are quiet servos as well. They probably do cost a little extra.