I found some unique helmets: Helm of Yngol and Helm of the Unburned that give fire or frost resistance on the head so i can give my followers
boots with 2 element resistances
the helm with the 3rd
rings/ amulets with 20% general magic resistance and 62 health each
Gives me 87 magic resistance for most all elements (caps at 85 and only 75 for frost with Yngol)
Armor with another 62 health and stamina
gloves with sneak and usually magika (as followers don't use much else there)
They also don't use much on the head except fortify magicka so I don't mind giving them one of these helmets as not all use magic and the ones that do don't pray and spray the way I do.
For myself:
I'm developing my suite of suits for each magic type. Currently running full destruction magic with 50% on illusion, conjuring and restoration. I just started using 2 element resistance on my feet instead of carry weight and one or two handed as otherwise I have zero magic defense. On the hands I'll use one or two handed and fortify magicka. Even when going one handed I often dont carry a shield. Thinking about making a full on fighters suit with stamina and magic resistance. Then I can reset enchanting and smithing... maybe.