The first helmet looks like it would be an enemy in a game like Half Life. The last certainly appears to be a guard or security agent, something you would see fighting on your side, guarding someone important. The middle however, seems to be too much of either side, and doesn't seem quite as original as the other two. It would seem a lot more different if each one was vastly different. That's the only bad thing I could see in this picture. The color scheme on the other hand, is extremely original, I have yet to see orange as a color used by armed soldiers, and I truly like the idea of something that different.
Enforcer might be less off the topic of this picture. You did a great job except with each of the three " Enforcers. " You should change a bit of each one. I certainly think this art was not original nor did it surprised me. I saw many pictures before I came to you but yet you did a great job. I would really wish that you actually think about how they would look before you even draw them. Although like I will say once more...nice job on this art. Now I am going to say this again.... EXCELLENT WORK ON ART!
Love the first helmet. It looks a lot more brutish with the "eyes" spread far apart and lends to the wide stature of the rest of the character. The first strikes me as a character which would appear as an enemy, while the other two seem a little more drone-like, neither good nor bad.