The tree shot is kinda grainy and I find that theres too much black dead space at the bottom. I really like the detail in the first one..if your looking for something to stand out I think #1 or the last one will stand out more than the tree shot !
By the time you read my post you might've already printed it out, but I would def go with the tree shot. Like crimsonandwhite said the tree will def stand out. It's a very interesting pic, and immediately jumped out at me. I spent the most time looking at that one out of all the others. The pier shot is cool, I like the perspective but it could have been taken at a different time of day with more dramatic lighting. i.e. sunset/sunrise dusk/dawn. Keep at it, and let us know which one you went with.
Wow, I'm surprised at how many of you pick the tree shot. I don't love it. Technically it leaves a lot to be desired. It's totally out of focus. I love depth of field blur, but this looks like hand shake blur. Yes, the concept is very artistic, but the execution was poor (Can you take another shot of that tree? It's worth a second try)
I like either #1 or, if you could up the contrast and boost saturation, the pier.