For me it would be Dunmer Ordinator armor. Hopefully this time not as a faction armor (in Morrowind u'd get attacked if seen wearing it by one of the Ordinators). For me it is the best looking armor suited to a Dunmer. It was totally unique to other armors we've seen throughout the games.

Other than that I like Mithril armor for an Imperial. I love the lore about it being made from the silk of ancestor moths.