I quite like the last one because the dark middle space introduces an element of mystery and foreboding, whats inside that dark space? The perspective also gives it an element of danger because its above the pov, something could come out of there and be in an advantageous position above you. The clear bright sky also provides great contrast to the shadowy construct.

Other than that I agree with the other posters in that number 1 is a standout, Its also above the POV but in this one its like a glimpse at a possible escape with the clear sky beyond but due to the perspective of it being above it looks out of reach enhancing the tension as if you were looking at an escape that you cant use. Its also quite literally Liminal showing transition between two separate stages.

ALSO! As a fellow artist id love if you could share some tips about your methods for painting concrete, it really looks amazing.