Level Up (A5E) Draconic Armor and the Duelist's Quick-Witted Defense

If a Dragonborn with Draconic Armor became a Fighter (Duelist) at 3rd level and gained that archetype's Quick-Witted Defense feature, which AC would be at play? The AC from Draconic Armor gift or the AC from Quick-Witted Defense?

DRACONIC ARMOR​

Some dragonborn grow tougher scales and sharper claws. These dragonborn tend to have short tails, wide faces, and broad shoulders, all of which are usually ridged with hardened scales or tipped with spikes. You have the following traits:

Claws. You grow retractable claws from the tips of your fingers. Extending or retracting the claws requires no action. The claws are natural weapons, which you can use to make unarmed strikes that deal slashing damage equal to 1d4 + your Strength modifier.

Resistance. You have resistance to the damage type dealt by your Dragon Breath.

Scales. You have tough interlocked draconic scales. While you aren’t wearing armor, your AC equals 13 + your Dexterity modifier. You can use a shield and still gain this benefit.

With an AC like that, I can imagine most players who are playing a Dragonborn and have this gift will aim for a high DEX score regardless of their class. I think they might also eschew manufactured armor because of this gift as well. Save themselves some gold.

QUICK-WITTED DEFENSE​

Also at 3rd level, while you are not wearing armor or wielding a shield your AC equals 10 + your Dexterity modifier + your Charisma modifier.

I am left wondering how AC will be determined with both features for such a character. Thoughts?

Tldr, whichever is higher.

Whenever you have multiple ways to calculate your AC, you choose which one to use.

So unarmored and with no shield? Whichever is higher of 13+Dex (Scales) or 10+Dex+Cha (Quick Witted).
If they're using a shield, they can still use the Scales' 13+Dex(+ shield) calculation

notably though, i think impenetrable draconic armor's +1 AC bonus would stack onto your AC regardless of what AC calculation you use, since it's not an AC calculation, but a straight up AC increase.