There seems to be a varying opinion on best color. Green generally by number of comments is preferred, followed by red and amber. Seems as if Amber is best in low light, dusk and dawn. In reality bright midday one just uses the crosshairs or post. If you google Trijicon best color you'll find a good deal of info.
In case you're interested after looking at some others, I have a new in box 3x9x40 Trijicon AccuPoint crosshair amber dot I would make someone a good deal considering it's cost ($760+-) plus tax (($60+-) for approximately $820 plus or minus.....would sell for $675. Bought it thinking I would put it on one of my rifles, but had a couple brand new Nikon Monarchs and Vortex Vipers sitting around that I opted for instead.