Just got both Dragonborn and Dawnguard.

Between the two of them, what's the best Heavy Armor set? I have Legendary Daedric that's been beefed up with enchantments. Still, would like to know if there's something better between the two pieces of DLC.

Thanks in advance.

Any.

With the right combination of buffs from enchantments and potions, you can smith almost any armor to hit the cap. It's just harder to do so with, say, steel than daedric, that's all.

For reference, the armor cap is at 567 if you wear four pieces of armor.
For each piece that you don't wear (I never wear a helmet), this increases by 25, as each piece adds a hidden 25 rating that doesn't show up anwhere.

e: That also means that the armor cap for a pure cloth wearer is 667