I would get rid of everything except for the Mecha Robot and the ACR. a few good pieces is much, much better than a bunch of stuff of wildly inconsistent quality.
A beautifully done environment, the lighting and materials look really nice! But I think the robot lets it down, it seems quite low poly and the texture seems a little basic.
is this meant to be an armor or a robot? because if its armor i would suggest sculpting a basemesh of whoever will be inside to get your proportions right, before jumping into the hard stuff.
I fancy "C" more... it just feels a bit symmetrical for a spider cycle... do you want it to be a spider cycle? coz I'm reminded with the robot from "The Incredibles"
It's probably just that I'm super lame, but I keep trying to turn that Robot's name into something more punny. Like Mecat. Or Meko (Mech+Neko). But good stuff!