I usually look for something that is distinctive when I purchase a G-Shock, and this time, it was the clean look of the watch when I saw it in person. I purchased the GD400 a few weeks ago online, after checking it out in person.
Even though the GD400 has a negative display, the display is the clearest that I've seen, as it helps that the alphanumeric characters are slightly larger than most other G-Shock models that have negative displays.
Here is the "Stormtrooper" (GD400DN-8):
Illumination with illumination
Illumination sans illumination