Okay, pics later because lack of time. Some of these are quite old ... Should work for new stuff.
first one is very well executed. Really nice concept aswell. Maybe a few textures in the background could bring more life to it? Nice lighting aswell.
Keep up the good work!
I like the first third and last ones. The first one is well done because of the smooth integration of each element. Along with the combined contrasts and smooth tones. The third is good because it's hard to make the whites flow together without over lighting the darker areas. The last one is awesome because i love abstract art. It really stands out to me.