Aspect ratios and how you see

3:2, 4:3, 1:1

35mm gives you 3:2, a long rectangle that suits horizons and gestures. 645 gives 4:3, closer to how most people frame instinctively. 6×6 gives a square, which refuses to favour either orientation.

Why the square is different

With no long axis there is no default direction, so composition becomes about the centre and the corners rather than left-to-right movement. Photographers who shoot square tend to describe it as slower.

Cropping later is not the same

Deciding in the viewfinder produces different photographs from deciding at the enlarger, even when the final crop is identical — because what you included was chosen for a different frame.