Clear lenses. I'd wear eye protection even if I didn't wear contacts. I wear cheap (but really good) sunglasses and it's not a problem to just shove an extra pair in my jersey pocket when I'll be riding in changing light conditions. If you had expensive sunglasses with interchangeable lenses, they usually come with a microfiber pouch to protect the ones you're not using - but you'd have to dismount to change them.