hmm.. i think the second one is better than the first one because the background fits the render better. transformers are angular, so it doesnt fit to have a plain smooth background.

that said, the second one needs to stand out more, to be more crisp. the render needs to stand out heaps more, its too small and to .. for lack of a better word, blended into the background.
these renders are ones good for using c4d's because they fit well and compliment the render. i havent had much of a look around the tutorials section of this site, but im sure theres a good c4d tut somewhere

the text on both signatures need work. they arent in context with the theme of the signature.