I like the colors and edgy-ness of #7. I also like the big z logo.
But, I need to be able to use this logo for different businesses under the Zanthia name - Zanthia Marketing, Zanthia _____________, Zanthia ___________, etc. The "Zanthia" might need to be worked into the logo or some way of making it more prominent.
I do not like the 3D effect of #8. I prefer a simple, clean design that can be used in a wide range of media.