get rid of the green spatter and work with the opacity of your blue spots try enhancing your depth with some slightly blurred background work besides that still a pretty nice sig
also add more lighting to bg to bring it out and that will aid depth aswell. and a lil more foreground effect for the third perspective, maybe more mechanical c4d work around his back
Version 3 is my favorite. It's still a bit too dark/empty on the left side, and it probably could use text of some sort. But other then that, great job on this. My rating: 9/10