which bubble is better?

myriads of lights

I am trying to do myriads of lights of some buildings on the background in the flash. of course, these lights must looks like flickering, and their colors will change as the time going.

I think the most important thing is to control the change of alpha parameter. Furthermore, when the buildings move towards the right and change their sizes, these lights have to be controled in another layer at the same time.

Examples: