I prefer Dual Wield as I find Two-handed skill line more specialized for Area of Effect (AoE). So I have to chose between Two-handed and Dual Wield. I will skip one-handed and shiled line as it definitly a Tanking skill line, All I want is to do maximum damage to a single target. I like toe-to-toe fights so I'm gonna play melee DD. You still can use Heavy Armor as DD (melee-chars will benefit from Juggernaut passive), but IMO you will do less DPS (although I didn't test this) Remember that maximum amount of stamina/magika affects damage done with abilities that use given attribute.
If these are magika-based abilities then consider of using Light Armor. If you think that most damage comes from stamina-based abilities then you should use Medium Armor in order to maximize your damage output. These lines can be magika-based (class abilities, destruction staff abilities) or stamina-based (two-handed sword, dual wield, bow, one-handed and shield) If you are DD(Damage Dealer) then you need to find out which line of abilities deals most damage proportion.
You shouldn't ask what armor should you use for some particular class, but for role that you want to fill in your group.