Brown or grey. To block the uv light most effectively, sunglasses of brown or grey are the best. These always have incorporated in them uv blockage. Other colors are mostly cosmetic and a few for special circumstances. None are bad for the eyes although some are not effective.
Blue = bad. Blue light is the most scattered and contributes to glare. Most patients find bronze or greenish lenses are most comfortable although the color rendition may be inaccurate. Grey lenses work well if polarized. Rose lenses can work on cloudy days - they have been known to make the world look happier... ;).
No color good or bad. If you like grey or brown, it is fine although there are tints for glare that can be more comfortable and they may be colorless.