The next step is to choose the voltage of the DC Lights. The most common options are 5 volt and 12 volt. If you really want to start a fight, go into a room and ask which is better 5v or 12v, and sit back and watch the light fight. So there is really no wrong or right answer, but generally, the United States uses 12v and Europe and Australia uses 5v.
DrZzs does a good job explaining the difference uses for them.