What's the best sunglasses for sun protection when hiking and just when outside in general?

Need to replace my sunglasses and figured I'd ask here since I use them mostly for hiking and being outdoors. I've always just gone with whatever looks good and feels comfortable, but I want to make sure I'm actually getting decent UV protection this time.

I see stuff like UV400 and 100% UV protection mentioned, but I'm not really sure what I should be looking for beyond that. Also, does lens darkness have anything to do with UV protection? Some of the really dark lenses I've seen don't seem to say much about UV protection. I'm considering a pair from Quay (flip side) right now but I'm also looking at Shady Rays and Chimi. Not looking to spend too much so please drop your best recommendations!