There's been a bit of discussion on the subject lately so I did some of my own research; partially because it sounds like most people are posting what "they" like best and/or helps "them" best and no one was providing data.
I know. Where talking about sunglasses and not something as important as whether to lift your pinky toe or big toe of your inside leg during the intiation of a turn, but I've been having problems seeing as well as I used to (hit the big 50 this year and I've found my clear goggles becoming my go to goggles more and more) so I figure I should figure this out.
I'm not going to offer an opinion on goggles vs. sunglasses, lens color, polarization, plastic or glass. Just providing a couple of links that I found informative and helped me wade through the data of what is really important.
What I like about the site, is unlike Manufacturers that brag how their lenses won't only protect your eyes, they'll also make you look taller and sexier, they aren't selling anything. I think many folks buy in hopes of being taller and sexier instead what the primary function of the lens is protection and to aid in vision.
At UV Protection on the left side click on caring for your vision then the sunglass shopping guide
Sport and Vision. Make sure to check out the "skill" link in the write up.
Hope this helps,