[Racer26]

Nearly everyone who's been around since the rotating light days agrees:

Bumper colors is the best way.

The flags sucked, they fell out of the holders, among other problems.
The LEDs sucked, you couldn't see them in anywhere but the darkest venues
2009's trailer colors weren't too bad, but they're kind of an extension of the bumper colors of 2010-present
and the rotating light, they were ok, but the lenses were easy to crack, and the thing was huge.