How to find which motor is the best

I know nothing about hardware (motors) and when I see projects like remote controlled cars or copters or walking robots… I always end up being quite frustrated like which motor is it that moves that.

If I wanted to do my own project how do I know which motor will be the best. (note that I don’t know how motors are supposed to be used or even which ones are out there) how do I go about choosing one. What process do you guys use?

If you don't have experience, it is probably best to buy things in kit form (or ready to go) from a company that does have experience.

If I wanted to do my own project how do I know which motor will be the best. (note that I don't know how motors are supposed to be used or even which ones are out there) how do I go about choosing one. What process do you guys use?

Look at sites that sell robots and supplies to see what they use, search google and youtube for projects similar to what you plan.

I would say first start by reading about DC motors, hobby servos, and stepper motors - these are the 3
commonest types that you would need, so find out what each can do well...

Secondly for all motor types there is the process of sizing (working out how powerful a motor you need),
which means knowing a little mechanics and estimating the torque and angular velocity you require. In metric
its simple, power = torque x angular velocity (torque in newton-metres, angular velocity in radians/sec).

Estimating torque without building a prototype can be tricky since there are many sources of friction...

And of course you might want reduction gears to match motor speed to what you want (they reduce
speed but increase torque, and lose a fraction of the power to losses).