An Amber lens is best choice. It provides excellent vision in both high and low light environments. In low level light (indoor swimming pool etc) amber lenses amplify the light meaning clearer vision in the water. In high light levels (bright sunshine, outdoors etc) they reduce glare which also helps to provide better vision and means you won't have to squint your eyes so much. An ideal lens colour for all enviroments.
The lens tint is the colour used to darken what you see when you look through a lens. Once you have been wearing a pair of goggles for a few minutes you generally won't notice the tint any more, but its effects are still there. Different lens tints are better for different weather conditions, some colours make it easier to see definition in the snow when it's low or flat light, and other colours are better at reducing glare from the snow when it's sunny. Lenses that are good in low light generally have a lighter tint and a higher VLT (visible light transmission), whereas lenses that are better in strong sunlight generally have a darker tint and lower VLT. On most goggles the lens can be changed easily, so if money is not such an object or you are a very keen skier, you might have a different lens for each weather condition. Below is a rough guide to lens tints for different conditions:
Overcast / Snowing - Yellow, Rose
Sunny - Orange, Gold, Blue, Grey
Allround - Amber, Rose
Night Skiing - Clear