me-
Oblivion
Daedric Cuirass + Grand Ring of Aegis + Mundane Ring + Helm of Oreyn Bearclaw
Daedric Cuirass provided around 15% armor, Grand Ring of Aegis 18%, the Helm (award to end fighter's guild storyline) around 5%. So combined with Aegis (Master Alteration spell) the armor rating could reach the 85% cap
Breton + Mundane Ring = 100% resist magic = magic immunity
BTW, Aegis Robe is in fact better, it's 18% from the start, equals to Daedric Cuirass at around master's heavy armor skill, and robes would not need repair. I just dislike Aegis Robe for it's appearance, and only wearing a cuirass looks far more better. Also I don't see the point of other parts of armors in Oblivion... without them you could still reach the armor cap, with much less encumbrance and repairs
Skyrim
I'm not quite familiar with Skyrim but it seems an endgame character doesn't really need anything.....Alteration spells fully progressed could provide 80% physical resistance (also the cap in the game) and 30% Magic Resistance, plus Bretons (25%) + Lord Stones (25%) again could reach the 85% gap in Skyrim
However in Skyrim a full set of armor is more meaningful that it provide some bonuses, so a full deadric armor also seem to be a good alternative
Again in both games light armor did not seem to be advantageous anywhere in the end...