I really like the last one, but the first two are so similar. They don't seem...different enough. Lol. I loved the last one though! It was awesome! Keep up the good work!
1. I love the colour and atmosphere of this photo. The focus on the guitar is good and the lighting is beautiful. I wouldn't suggest changing anything.
2. The contrast of the guitar against the black and white background is effective but I think you should have cut around the person more carefully -- I'm assuming that you've cut him out and pasted him on top of this second photo?-- because he's missing quite a bit of his head and there's some white around his body. It's a good photo though and there's a nice use of space.
3. This one really doesn't catch my attention. It isn't focused enough and there's nothing interesting about the background.
