6. Superior Brushless Motors are ideal actuators
What are they? DC motors which need specialty hardware to drive them. 
Good: High efficiency, it's the most efficient option available.
Bad: Controllers add expense and complexity.
7: Stepper motors, for when you want a self balancing loli
What are they? A DC motor which uses four wires to drive the motor through pulses allowing high control. 
Good: Very accurate with great control. They also offer high torque for their size at lower speeds. They can hold a position. (Most other motors will burn out unless they have protection circuitry) Comes in Nema standard sizes which makes designing around them a great experience.
Bad: They require special drivers to function. Low efficiency unless they're rotating at a specific range of RPM. 
(Because of their great control characteristics, they're fantastic for small self balancing waifus)
8: You, yes you Anon!
What? You can pull her along with you.
Good: She doesn't consume power while being pulled. Could generate power while being pulled. Will be right beside you.
Bad: She's completely dependent on her Anon listening to her for her needs to be fulfilled. (Potentially a plus if you dig physically disabled girls) 
Feel free to add or correct anything!