[NOOB] Controlling speed 4 small DC motors

Hello all,

I'm completely new to Arduino, and would like to start with a simple project.
My idea is as follows: I have 4 DC motors, and would like to control the speed of all of them at the same time. I have some kind of slider switch in mind.

So my question is, which model should I get?
(Though please keep in mind that I will probably end up doing something else with it in the future.)

Thanks in advance,