Is flat AD better than armor pen vs tanks?

The only ADC I could see not requiring armour pen is Vayne, all other do require armour pen if there is a champ on the field building armour. I believe the rule is above 100 armour and you should consider armour pen. Although I am unsure on my last statement. Maybe somebody will come up with the math behind it for you.

In general, %APen is more useful against tanks than flat AD (ie items like , not lethality items like ).

However, I don't know for Jhin. Here are the most popular core builds from OP.GG

https://i.gyazo.com/aebd37b0fd1b4db3300d09e271590527.png