Tough one, I can't definitely answer¹ this. I like Steel, Nordic Craved, female Ancient Nord Armor, the Dawnguard one, the Solitude guard armor, Elven armor, the Imperial light and heavy armor, Wolf armor... The list goes on.
Unlike most people, however, I don't like Dwemer armor.
¹Actually, I can: All of the Dunmer armors.
I think the Dawnguard armors are the best looking sets in the game, heavy or light. The heavy gauntlets and boots are good combined with other heavy armor to make a 'medium armor' look while using only heavy armor.
I'm also a fan of the Stalhrim sets, Steel Plate, Nordic carved, Orcish armor, Dragonscale, Ancient Falmer, Steel, Glass, and the various Hold guard armor sets. I prefer mixing them together rather than full sets.
My favorite outfit (currently) is: Dawnguard Heavy armor (white variant), with Steel Plate Gauntlets and Steel Nordic (or Steel Plate) Boots. Helmet is either Steel, Dawnguard heavy, or Rahgot (I like the mask). With a Steel Greatsword to complete the knight look.
I think the choice is obvious and you've all gone horribly wrong .
Bonemold armour is hands down my favorite. Though I do like Steel Plate, Nordic Carved, Ebony, Steel Dawnguard Heavy Armour, Dwarven...Alright so the Heavy ones, big fan of Heavy Armour...
IN terms of Light Armour... Well I like the Thieve's Guild and the Leather Sets...
Blackguard would be my personal favourite. But I also really like simple iron, hide, scaled, and leather armor. Mainly use light armor, nonetheless, but I like the aesthetic of the earlier armors. I find it easier to rp when my character looks as though he could simply be any other npc, I guess.