Here they are with the image rotated 180. I prefer the one on the left as the darker area is at the top.
This is what I think works well:
- there is good variety of value across it
- the strong lines are repeated in different sizes
- the concept of a grid is more consistent
- there is a more constrained colour palette
- it appears rather chunky/blocky
- the right side of the piece is heavier
But here is #2 as a horizontal piece and I find it far more engaging with more movement than the previous orientation. However the centre bottom needs a little more colour.