#1 and #3. pleasing curves, bends, lines and reflections. Your subjects are unique characters.
In #1 the background just works because I can see that it includes trees, so it does give a slight sense of place, but I would agree with isaac, more would be interesting.
#2 I think you tried to include too much. Did you have a hard time deciding what you wanted to include? So, you ended up trying to include it all! Was it the tree on the right , the reflection in the foreground, it looks like a sunken tree there, too, or the sky that caught your attention first? Then you have some random stumps. In the right side background there are other things or shapes that are hard to identify. Why did you include them? The clouds, too, are interesting, but you lopped off the tops. Do you see what I mean?
If you had included just one of those elements, foreground water and reflection, or the exposed trunk on the right, or more of the clouds, less of the foreground and a clean background, maybe that would have been enough, rather than including some of each.
My bias is to have a subject that really jumps out at me. I would be satisfied to see a lot more of that tree, up close so I could really see its character, texture, and shape. That is why # 3 is my favorite. The B&W works well.
