1. I really like the contrast of the dark tree and sky, as well as the color of the sky. I wonder what the photo would look like with the wire above and houses below cropped out.
2 & 6. These two are my favorite and I don't know which one I like better. The B&W captures the feeling of hard concrete in 2. On the other hand, the colors really stand out in an otherwise stark photograph in 6.
3. I think the sole reflection of the crane in the building's glass is really cool.
4. You have a neat effect going with the sunrise/set(?). The first thought I had was, "I looked at the flash".