AR6's are stiffer, heavier, wider and non symmetrical, so pretty much more of an all mountain ski. Invaders are lighter, more narrow, symmetrical, and softer. Invaders are more of a jibbing ski. As far as durability Armada trumps the Invaders.
well i ride park alot like 95% of the time. and i ride urban a few times a year. I only ride pow like twice a year so thats not a huge concern of mine.
Invaders you have to center mount there is only one position on them, for the AR6 you can play around with it more, but since you said 95% park I would go more toward center. what size are you looking for, I have two demo skis from last year in mint condition 161 and 171