The Quad. No “s.”
The Quad will have more of the typical freshman dorm experience from a social perspective. The Harrison social experience will most likely be limited to your floor.
The bathroom situation is not a reason that I would personally choose or not choose a dorm, but YMMV. However, you clean your own private bathroom.
The film series in Harrison is not limited to residents, if that makes a difference. Plus you can attend the screening sessions without being registered for the class.