I like the Nightingale armor, a lot... but my preference is still the Dragon plate. There's just something about killing a dragon whilst wearing the bones of it's pal
I can't decide on a favourite. I like them all but I wish there was more armour sets. Some of the helmets are ugly and could do with a change too haha.
I like Elven because it has eagles on it. I usually wear armour that fit the style or role-play I suppose. So if I made a Thalmor Altmer spellsword I'd wear Elven, if I played an Orc I'd use Orcish, ect. I usually wear robes though since I like playing mages. I just wish there were more of them with different varieties.