We can't tell which color of sunglasses lenses is best. We shall put this question in a certain condition. For example, yellow lenses are best choices for shooters, and rose lenses are best choices for people who stay a long period of time in sun while dark lenses are best choices when you strong sunshine.
The most common color for sunglasses lenses is dark grey which can transmit all colours evenly without distorting them. It won't impair vision and can provide overall protection from both glare and UV rays. Most eye doctors will recommend you to get sunglass with dark grey color.