If you enchant your armor do you add to it's defensive properties like Fortify Light Armor or Protection From Shock, or do you enhance your attack ability and simply trust in your armor skill to protect you?

Well, heavy armor on it's own provides a superb protection, especially high tiers. So on it's own you don't really need to add more " fortify " or absorb magicka/spell resist, unless you wanna create an uber tank of a character.

Light armor however, would benefite from additional armor rating/spell resist and so on, since the protection it offers is quite meager. Then again, light armor is mostly used on sneak builds, so, I guess it doesn't matter that much, and it's more about pure offense.

I like defense so I generally add either extra health on armor, health regen, spell absorb/reflect and so on.

Enchanting for extra defence becomes pointless once you can smith to the cap. Any enchantment I put on armour is for carry weight, sneak etc. to offset the downsides of using the armour, and I usually don't go past the break-even point. E.g. Fortify carry weight only by the weight of my armour, so wearing it is the same as leaving it at home.

I have several characters (some of them mages who use Bound weapons) who don't use armour at all, even with melee attacks.