Diana F+ : you have plastic masks that you can change - 40x40 mm, 56x56 mm and panorama mask. Also there is a pinhole option. I had diana F+ and now I have holga (holgaroid actually) - I don't see much difference in final prints.

Some say that old diana (not F+) was giving dreamy and nice pictures, but I did not try that one (yet ).

regards,