#159 Interesting logo, I like how it's eye-catching and gives the notion of action, but it doesn't really hit on the themes of 3D and layers like the other top entries do.
The cool thing about #159 was that you could see a line of empty space going through it - with #164 and #166, that coolness is lost. Even though they do have a 3D aspect, #159 works much better.
#171 Interesting idea, and I like the shading on the graphic, but the S looks very thin and insignificant.