Ebony Mail (Boethia's Calling) with Nightingale Boots and Gloves on a female character looks amazing. Swapping the Hood for a Silver and Moonstone Circlet, or the Guildmaster's hood (Thieves Guild) works too.
Scaled Armor in general looks good on both male and female characters. My only gripe is that the hide and ringed lower half of the armor looks too bulky on most females.
Thieves Guild armor and Guildmaster's armor both look good. Linwe's hood makes the suddenly-bald-to-avoid-clipping-issues character heads too apparent.
Ebony Armor is a winner in my book, it looks better on Males though, while the Ebony Mail from Boethia's calling looks much better on females.
Iron and Banded Iron look great on both Male and Female.
Elven Armor looks good on both Males and Females, but the color is a little obnoxious. I would kill for a neutral color like grey or even a cobalt blue such as the Nenalata crown in Oblivion.
Dark Brotherhood Armor looks best on Males. The shroud is the obvious exception, but other than that, the front of the Dark Brotherhood armor on Females doesn't look "Right".
Glass is always ugly. The male version is generally better. Had the Front portion of the Glass Armor matched the Back, I wouldn't complain, but the construction of the glass armor's chest section throws off the "Light" look. The boots and Helmet have too much pointless "Flair", such as odd protrusions of Glass that seem more like a liability than protection.
Daedric looks good, much improved from Oblivion. The helmet is my favorite Daedric (And full) Helmet in Elder Scrolls history (Trumping even the Daedric face of God). Daedric armor only has 2 visual drawbacks in my opinion. The oversized shoulder spikes (Should have been optional, like Steel Armor's pauldrons) and the somewhat obnoxious red glow.
Dragonbone is ugly, but it's ugly that makes sense. It looks like it's a hunk of bone fashioned into armor. Dragonscale armor looks okay on males, and absolutely hideous on females. The helmet is probably the ugliest headgear in the game. The chest section looks fine on the Male mesh, but the dragon-skin underlay forms sort of a "Skirt" between two scale plates protecting the upper leg, which should have been removed.
I should probably add that I don't think Light Armor has any good looking Helmet. Most of the hoods for matching sets (Nightingale, Thieves Guild) look fine, but those aren't really "Helmets" now, are they? Diadem of the savant compensates a little.