sorta reminded me a bit of super metroid... not sure why...
all of them, with the exception of the first, appear to look a bit metalic, was this what you were aiming for?
If not, I'd have to say the first one. If you were going for a metalic look on the otherhand, i'd say I like the blue ones.
The leg does look a bit odd, though I'm not the person to ask whether it would impede movement. I think alot of it has to do with your imagination and if you can animate it without it looking too awkward.