I like browns for the same reasons some mention amber. Serengeti Drivers were for the longest time, (and mostly still are), brown due to the idea that this provided the sharpest detail in the locations we are going to be traveling most frequently. They do make colors more vivid, beyond actual tones of a given spectrum, this may or may not be a plus. Personally, I find long term wear in brown to be the least fatigue inducing, greens which are said to be the best in that regard, do not work as well for me. I haven't tried the reds outdoors, but testing indoors at shops, rose tints seem just a bit "off balanced", not bad, just odd. I ran across something in a cycling book on the topic of lenses that I hadn't considered before, about polarized lenses in a road application. I'm just repeating this, not sure if I even believe it, but the author stated that polarized lenses may not be the best for road use in a wooded or heavy plant covered area. This is due to loss of contrast in the dark areas of the road surface to the adjacent shaded areas of nearby trees and such. Author goes on to mention while great in distance glare reduction, the closest bike stopping road hazard is going to be in the most obscured portion of the vision field due to the nature of the polarized view. Stick, suicidal bunny, possum, deer on a power trip, thrown hubcap, etc. While there is some real science involved with it, color choice does seem to me to still be somewhat a matter of what does or does not please a wearers own eyes.