The brown elephant in Andersonville on Clark is also a great place to donate clothes. Very friendly and for a great cause. I prefer going there as opposed to the drop boxes. Who knows where those clothes go.
Please be mindful that many of these boxes are scams and for profit businesses. Better to drop at a shelter so u know your donations are going to people in need and not sold. Cornerstone community outreach in uptown is awesome as is Pacific Garden mission.