Which the bicycle brake is better?

For bicycles,there have many kinds of brakes.Like disc-brake,v-brake,caliper brake,and others.How to choose a better brake for the bicycles?You know?

Firstly,generally,some kinds of bicycles have the match brake.For sample,almost,V-brake for city bike,caliper brake for road bike,disc-brake for MTB. However,sometimes,the mechanical disc-brake braking effect is not better than V-brake.Compare these two styles.

So when you choose a kind of brake,if the disc-brake price is cheap,and not hydraulic disc-brake,we suggest that use the V-brake,the braking is better than that.