Seeing these next to each other it is amazing to me to see the differences in look and attitude between the various sculpts and what could have been. I witnessed the creation of some of these masks, from roughly shaped, such as the JRX and Darth Stone helmet, to the pieces of art they turned out to be. The others I only saw in their finished version, but they look amazing too. Personally I like the concept version that the JRX and DS is taken from and it is interesting to see that the same artwork can be interpreted so very differently and end up with very different attitudes and looks.
The JRX looks narrower and more single minded in its closed-in dome around the face - one mind, one thought, never relenting, never stopping, but zeroing in on any given task and dealing with it brutally and efficiently, whereas the DS helmet, with it's flaring dome and flaring cheeks almost looks like its enraged, screaming, roaring hot fury that will lash out and break you apart - angry at the world and charging in to unleash the hell roaming within, behind that mask, but will never find pleasure, regardless of how much mayhem that he causes.
The eFX is interesting too in its own right. Mechanical and methodical: more man than machine. More of a thinker, than a fighter, less rage and more intellectual, but ready to slice you in half if you cross him and he won't think more of it. He's a schemer and a tactician who plots and makes plans to rule the Galaxy.
The Kropserkel is very different. Much more simple in its design, appearing almost like it was meant to underwhelm and make people underestimate the person within. Stealthier, sneaky, who'll lurk in the shadows, waiting for his chance to stab you in the back and disappear back into the shadows. Much more of an assassin, agile, fast and you won't see him coming. A whole other different approach to the other concepts.
And then there is the movie mask. Sophisticated, stylish, less mechanical, but fierce and aggressive with all those angles and shapes and sharp edges, yet also thoughtful with those large eyes. Much more of a battle helmet and the lack of emotion in the face in essence makes it more terrifying, as the attitude of the wearer will color the expression.
Would love to hear other people's thoughts on the various styles.