Hi Nick! Welcome to the forum.
I like this series overall. There are a couple of standouts for me. I agree the first shot is really good, but I don't think it's the best - that would be the third shot, for me. It's a little contrasty (very deep blacks and extreme highlights) but for this particular shot, it looks great. It's fun to learn to play with contrast so certain images can pack a little more punch. I think you'll look at this one down the road and like it even more - it has a great feel. :thumbup:
What follows, the 4th shot, is quite flat - very gray tones throughout. I think Charlie is right when he says the lines of the lumber are drawing your eye into the shot, but it's not a real strong composition. However, visual interest could help it if there were better contrast. For instance, I can barely make out that roll of twisted wire, which you probably used as part of the composition. Richer blacks here would help that wire pop into the shot and add some drama.
The last shot does absolutely nothing for me, I'm sorry. I am not a huge fan of selective coloring, anyway.

Here, the unreal shade of blue lends nothing to the scene. It is true that sometimes *unreal* colors can be effective, but this has no feel of intent behind it, just an arbitrary attempt at an "oh wow". :razz: I'd like to see it in plain B&W!
Let's see some more!