Of the set, I find mysel attracted to the 2nd one. I like the feel, subject and scale of that image. Here is a thought for your consideration. With the image of the tractor, try a slight crop (4x5) where the right side of the image is cropped out leaving the drive and fly wheels. I feel it may lead to a stronger image that shows scale much better than your current offering. Thank you for sharing your images.
I agree with David, the second one attracts my attention right away. In the first image it seems like theres a lot of open space on the left side, making it so youre not attracted to the barn right away, when i first saw it i immediately noticed the open space instead of the barn so you might want to try and crop it a little bit, and the second one i love but i feel it may look a little better in color but that could just be me.