[Dave G]

I've had a couple of iridium ones and will cheerfully get another too. They scratch very easily but in my opinion the black ones are too dark and even in overcast conditions make seeing anything on the road ahead problematic.
Iridium ones have less of a tint to see through as the light is reflected away from the inside not just absorbed, they cut out as much light as the black ones but will not seem as dark to see through.
A matter of choice really.
....black ones are cheaper generally.