This one: 
90% of the time I see it here, it doesn’t indicate confusion but rather the shitty, superior attitude on the part of the person using it. ‘Oh I’m just so CONFUSED as to why you would do/buy/say that, instead of doing/buying/saying whatever I, as a superior sort of person, would do/buy/say instead!’
this face is similarly, but slightly less, infuriating.