Both are looking very nice. I'll let this run for a while before choosing, I'm generally too impulsive when I buy artwork (and I want this to be my best sig ever!).
Improvements:
Anomader - Try some sort of Junkerish mechanical border like pipes and stuff. It looks a little clean for a Junker sig; if the congress symbol wasn't there, you wouldn't know it was a Junker sig.
Schlurbi - The congress tag is slightly off, you see it must be lowercase and the colons must be close to the top of the j, Anomander has the tag pretty much perfect. The tag also needs to stand out a little more. Also can we make Nick's face fully opaque? I can see the grid lines in his cheeks.
They still look awesome though and I look forward to seeing what you can come up with next.