This is a different world to me... ha, well, it's sci fi... du'uh,
anyways, from the whole graphical feeling, i like the bottom one a lot. It has nice shapy... contrasts and i like the weight of the lines and how you distributed the areas.
from the design, it's hard to tell. I am somehow quite intrigued by the 3rd - because it has some kind of twist in it - a machine becomes a bit more organic and "used by a human", if there are elements that twist in different perspectives. Hard to explain. Maybe that's unintentional or even an unwanted mistakes, but for me, that makes it more interesting : )