These are all so kickass; the designs and details are beautiful, it looks like you worked hard on them. It really shows. My favorites would have to be Bone Breakers; the name is just grand, Platinum Fists; the style is lovely, Assassin Knuckles; it's small and good for not being that noticeable, Plasma Knuckles; plasma is just awesome, and Magitech Knuckles; the design is dazzling, it has magic and it fits on most of the arm.
(sorry, there are some words that i still don't understand)
And as for the Magitech Knuckes magic stone it really depends on what one element your going to used most of the time.