Ignoring the previous post which is obviously from someone who is a bitter, mean, and vindictive person, i would say that you should most definately go for the AC and the all around better piece of armour. Having said that, i play a Troll cleric (almost defiler) and i spend most of my time jealous of the power pools of those filthy dark elves and erudite casters who proliferate the lands in and around the commonlands. Having said that, there is a piece or 2 of greyed out armour that i haven't upgraded yet simply because i'm loath to throw away the added Wis on them, but if something new and shiny passes thru my inventory, i'll snatch em up, regardless of the wis.