I would not recommend Friedrichshain, Neukolln or Pankow. Friedrichshain is ugly and boring, Pankow is racist. Mitte is far prettier than any of these, Prenzlauer Berg has been gentrified into a generic boring district that could be anywhere in Europe. Holiday flats and AirB&B should be avoided completely, stay in a hotel or hostel if you want to visit Berlin. Thats what theyre there for. Stealing peoples homes for your holiday is shameful.