82% amor pen vs AD which is better?

With These to items on there own + + 7% from masteries, you get the following.

• 82% armor pen
• 100 ad + 1.5% per 50 hp difference.
• 300 hp
• 20% cd Cost is 5800 gold.

Normally Adc would get + which gives you

• 70 ad + 120 magic dmg
• 50% crit
• 5% move speed
• 35% attack speed For a cost of 6200 gold

Now my question is regardless who you attacking is 82% armor pen not more worth it, i mean 82% off of 200 armor or 60 armor is such a major thing. Armor -> whats left 60 -> 10.8 80 -> 14.4 120 -> 21.6 160 -> 28.8 300 -> 54

So can someone please give me their opinion, i mean it looks to me like all AD adc's should rush this? what you guys think