Like Juro said, everybody's eyes are different, but in general, here's some good info I borrowed from another website:
� Gray or green-tinted: Offer the least amount of color distortion; good for all-purpose use and clear days.
� Amber and orange: Block blue light, offering a brighter view on cloudy, hazy, or foggy days.
� Gold and yellow: Add contrast; best in flat and dim-light situations.
� Brown: Best for enhancing depth perception.
� Rose: Has the highest contrast and best low-light image resolution.
� Mirrored: Reduces the amount of light that reaches the eyes; good at high altitudes.
� Gradient: Shaded from top to bottom. (A double-gradient lens is dark at the top and bottom, and lighter in the middle.) Driving glasses are often gradated so that you can see the dashboard clearly.
� Photochromic: Automatically darkens and lightens as light conditions change. Photochromic (transitional) lenses won't get very dark, and take some time to adjust to changes in light. Heat also hinders the photochromic (transitional) lenses from getting dark.
Tip: Darker doesn't necessarily mean better. The darker the lenses, the more visible light they block. Brighter conditions demand darker lenses. It's important to keep in mind where you'll be wearing them most. Sunglasses designed for mountain climbing, for example, generally have lenses too dark for everyday wear.
My passion for catching fish is eclipsed only by the fish's passion not to be caught.