I would prefer the first head more but oh right after all it is for quicksilver set request i presume.. The rest looks really nice. Really great 3d-ish effect going through all parts except for the sides of torso. props for the fact that the torso isn't all the same texture. Nice flow also. 9/10 If you really want it to be rated.
Also as for wrists or legs. Don't do fingers. Do something more robotic. Like cannons or other stuff.
realy like this one. clean work. the first head is better IMHO.. Try to make cannon - one hand text, and robohand other.. thats will add assimetry to this set and make it even better..