I touched upon this in my last thread, but it seems to me it could deserve its own discussion here.

I havent tried all the classes, and i have only reached the later stages of the game with 3-4 characters, as i tend to get bored once i discovered 'yes they are good' or 'actually this class just svcks'.

I havent tried pure unarmoured mage
(because ive always thought, why not just wear some armour and hold a sword)
Nor have i ever exploited alchemy to its deadliest, I made some pretty potent potions, but never needed to use them because my characters had other,more fun talents)

But i have explored a wide variety of mage-warrior/ mage-archer combonations.

Anywhoo... Enough about my experiences, I was mant to ask first if there is a class combination that is flat out More Powerful than anything else before i was to suggest if we should have a discussion about the candidates. answer, then candidates.

Pure cloth mage without a doubt. Illusion is unaffected by the difficulty slider and you must not wear armor to affect the highest level enemies with command and frenzy.

Plus paralyze and invisibility.

Conjuration is also unaffected by the difficulty slider, well at least the summoning spells and turn undead also requires no armor to affect the highest level enemies.

Then there is weakness stacking with destruction, and it is easy to achieve max armor rating with alteration.

Between alterations elemental shield spells and mysticism's reflect and absorb spell, you can defend against magical attacks.

Breton Atronach, custom class, +Str and +End. Wear cloth (shoes/pants/shirt/hood) enchanted with elemental shields to achieve 85 Armor Class with no actual armor. Other enchantment slots go to additional spell absorption and resist magic, OR Fortify Magicka with Sigil Stones. Pure mage, or melee-mage hybrid. First few levels will be tougher until you can gain access to custom enchanting. Alchemy is your friend for magicka recovery until higher levels when everything spams spells, by then you will be able to make monster Restore Magicka potions as well. +5s to Endurance every level until it is maxed (for max health). +5s in other attributes as fits your character.

Actually any intelligently built melee/mage hybrid with Atronach birthsign combined with Alchemy and Enchanting can be near god-mode in this game. Some races work better than others for it, depending on starting Endurance level and resistances.