The first image with the pier placed in the centre seems to take up all the room in the frame not leaving space for the eye to move around. With this image, the bird towards the right of the image add a welcome bit of drama but your eye seems drawn to the big block that is the pier in the centre.
Moving the pier up to the upper third, and slightly left of the centre of the frame and revealing more of the beach, seems to allow the eye to move up to the pier. This seems to allow the eye to move more gently.
With the 3rd and 4th image, placeing the pier closer to the edges of the frame make the pier look my dynamic.
The 5th image for me is the one I prefer as the placement, with the top of the pier approaching the lower 3rd of the frame, allows the clouds space to add drama to the frame. The contrast between size, shape and tone of the 3 elements, the sky, the sea and the pier seem to meet the expectation of the proportions and placement of these elements. The sea feels right being that low in the frame. The pier sits with the left vertical 3rd running through it's centre and the space the sky fills adds movement to the image with the dark storm clouds.