Aesthetically, I prefer the basic steel armour (with or without shoulder guards, but preferably with). It feels more nordic than any of the other available pieces.
Statswise as a heavy armour guy on my first playthrough, Daedric wins out on sheer practicality (rarity of daedric hearts be damned).
Light armour wearers are probably best served by either dragonscale, or nightingale (I've not really checked out light armour, so this is merely best guess), but I couldn't tell you what looks the "coolest" for light armour types.
Just personal opinion of course