We like the 3D look of the graphical element. Also, the gradient in the letters is nice. However, the design looks better when larger, but we prefer the linear look of #13.
We truly appreciate your efforts and responsive. In fact, yours was the leading candidate on the first day. However, we found that your concept is reminiscent of the AT&T logo, thus we moved away from it. I wish you the best of luck with future contests - you are talented and are bound to win some.