One of my favorite songs of theirs is "Skinny Love", which has these really cool guitar strumming parts in it. Recently, the 15 year old British phenomenon Jasmine Van den Bogaerde (AKA Birdy) did a cover of this song, which although it had a bit of a different vibe from the original one, was also astoundingly listenable and enjoyable. Below, I've posted both versions so you can decide which one you prefer.
Bon Iver - Skinny Love (Glastonbury Concert)
Birdy - Skinny Love (Official Music Video)