Green. You will percieve it to be the brightest, even more than the white. I guess it depends on what you want a Glo-tube for though. If it is for an emergency blinker, you might want red, as most people associate that with a warning color.
White. I have the amber GT and it may not be enough to prove useful for camping and outages, although certainly enough for map reading. Amber would be ideal as a marker, or for sneaking into your house after a night of partying w
/o disrupting your dark adapted vision.