I would go with the one wing going faster than the other scenario. Seems to make
intuitive sense.
But as with many things in flying your intuition would be wrong, or at least incomplete. At the risk of being boringly repetitive - the outer wing is only going faster while the aircraft is yawing, and yet the yaw-roll coupling still occurs after the aircraft is not yawing further but is in a yawed state ie going sideways through the air.