Now Siena Blaze would have been my first choice...but then i thought a little bit and decided that as VILLAINESS she is perfect. Hateful and punchable. Not the best one mind you, as she has no shread of sympathetic or endearing trait whatsoever, but serviceable b-list villainess that you LOVE seeing Storm punch in her smug face. So far so good.
X-cutioneer had good design(loved it), and possibly interesting idea(I always thougth about the possibility of a human going all punisher not against the mutant per se but those that caused the hate toward mutants as well as those who murder innocent mutants.) But in the end as was said gone....nowhere. Probably would have worked better if he had been introduced in the 80's the peak for vigilante characters like that. So yeah kind fo worst
But my choice would be Gamemaster. He was...so bland...so so so so very very bland. If you had brought him back to the memory i wouldhave forgot he ever existed. Annoying little ***t she is at least you remeber Siena as the pseudo evil Jubilee of X-men