Hmm, I like that third signature.
Since you said you wanted comments, I will go ahead and comment on each signature that has been posted.
Tag 1 :
First thing first, there is text going over the renders face.
I think that should be avoided, the text should be placed a little lower, and it would look better if it was smaller, those huge characters take a lot of space
from that tag, and there isn't much space because of dimensions.
Also, work with getting more depth and making it look like there is a light source, it would help if you darken/blur the background a bit, and also make the background blend with the renders
Tag 2:
Not much to say about this, I don't have much of an idea what that is supposed to be, but the background looks like it is
saturated too much, and it also seems like it has high contrast.
Tag 3:
Looks fine to me, although there are dark parts in the background which are just black, I really wish those were filled.
Tag 4:
The render doesn't fit with the background, I don't think those colors go well together, also
there was no need to duplicate the render, and post a lower opacity image of his face next to the render.
That is all I have to say, try getting familiar with C4D's, try giving yourself a little more space to work with (higher height in dimensions), and
don't over do it with the text.
Good luck!