Magic Damage or Intelligence

[Klamor]

If I could widen this:
My Paladin has two Untradable Bodies she can wear
Kokoroon's Darkshell Mail - 102 Def, 102 MagicD Str9 Vit 10 Parry 9 Acc 14
Aetherial Mythril Haubergeon - 76 Def 57 MagicD Str 10 Vit 11 Acc16 Arit 15 SkillS 14
Which would you choose and why?

The Mail is higher defense and magic defense, and is actually designed for tanks to wear. The Haubergeon is high defense, with lower magic defense, and is actually intended for use by Dragoon. To answer your question, as the tank you should choose the Mail because that's what impacts your survivability the most.

For additional information. Be sure to keep in mind what color the item is as well. A Blue piece of gear (rarity) will have a higher overall strength (read: apparent power level) compared to a White piece of gear of the same item level. Along with that, High Quality gear is [obviously] superior to Normal Quality gear.