Both the iron and steel armors look pretty good. I admit that I tend to want to keep a horned helmet through the whole game; even though the Scandinavians didn't actually run around with horns and wings on their helmets, the horned helmet still fits the popular feel of a Viking.

I'll have to take a closer look at Imperial armor - if it's a pretty good version of Roman legionary armor it ought to be pretty decent.

I haven't seen much of the other armors. I've found (and sold) a couple sets of Elven armor (I'm going with heavy armor) and I can make Dwarven armor, although I haven't yet because of the expense, but I haven't found any out in the world. Both look pretty cool but tend to disturb the feeling of being a Nord Viking due to their more outlandish look. Haven't seen Orcish yet.

I think Glass looks terrible. It is like a bad Christmas tree ornament. Same for Elven, except it looks decent on Redguards and Khajit. Dragon armor looks goofy. Daedric looks a bit too darkity-darK-dark ostentatious. Dwarven is ugly.

The best looking generic heavy armor I have seen is Steel Plate. The best generic light armor is leather.

I am otherwise a pretty big fan of the Whiterun armor. Too bad it is weak. The Imperial and Stormcloak unique armors look great also.

It is too bad that the best looking armor is seen mostly in the first 5 levels of the game.