I like the stand alone boxes in #2, 5, 13 and 4. I like that I'd be able to just use that part of the logo on certain items. Entry #6 is nice, but with the line running in the middle of the "C"s, it makes it sort of look like "G"s.
I've been thinking about negative space, and I'm not sure I want it. What would some of these look like without the white negative space. Maybe if it were black or perhaps another color.
I really like your design as well. I was wondering if I could purchase that as well. I wanted to have them both, but not sure if the website allows that.