For now robes and heavy armor, as soon as I'm able to enchant something that comes close to the archmage's robe I'll go full heavy though, I suspect it will be most helpful once destruction stops scaling.
You won't be able to enchant anything close to the archmage robes, not without serious abuse of the crafting system. Still you can't make an item that fortifies all schools.(ever), And without fortify enchanting you'll only get +62% to magicka regeneration.