I've found Serengeti (Vermillion KN6444 model) to be excellent, and provide surprisingly good definition and depth in grey weather also. Mildy photochromatic, 100% UVA, 98.5% UVB, glass lens. They've been good at replacing them for me free of charge downstream if you break the frames etc. I think around US$80-$100 but about AUS$300 here!