I am choosing Sketch number 3 because it allows me to use repetition, vertical lines and unity. 

I could have repetition of rectangles. Unity in the size or shape of the buildings. And Unity of colors in the whole image.

I will redesign my pendulum as a wrecking ball going through a city and knocking down buildings. I will make an effect to make a building crumble down and turn to nothing. The wrecking ball will hit it and go straight through the building with ease before the building collapses fast onto himself.