I'm a fan of the Polaroid (Impossible) black and white now, though I can't say it makes sense to pay $2.25/frame retail. But the contrast is good, and it develops at a reasonable speed now.
My SX-70 didn't focus for the Jewish Museum photo (center top), but was able to handle some very challenging lighting conditions (the rightmost image), which was a photo of reflections in shade on a backlit building.
