Hmm... I'm going to hit you with some critique. Please don't be offended! Your work is great and you have a keen eye on blending the image into the background, however, it seems to be a bit too much at times.
My two favorites are #3 and 4. Both banners are lovely with the colors. The focal point is directly towards the images, which is great. You do however, need to work on the font you decide to chose and the way you use it. What do I mean? Lets talk about banner #3, you have a square white box and on top is the text. Sure it looks somewhat good, but it can be fitting and finer. Since the box has nothing to do with the background nor the image, it seems to be out of place. It's better if you would actually take it out. The font can also use some work. This piece gives off a sincere feeling, so it would be great if you use a much tranquil font that's more suitable to the banner.
You used the font in many of the other signatures, try to change it up. I used to do the same exact thing. Check out other graphic artist work and see how they set up their font.
I'll leave you some feedback later. Work on the typography a bit and I'll be sure to comment back!