I think % armor penetration is gonna be the most abused stat next patch
With the changes to Lord Dominiks and Mortal Reminder coming next patch, I don't think tanks will be a good pick anymore. They are basically gonna get melted by ADCs every time unless you've got damage reduction in your kit, wait TRUE DAMAGE is being added to crit now with Infinity Edge. Well GG!
Patch 8.11 will make tanks just really ineffective in soaking damage because that 300 armor build against a full ad comp will just be negated by that ADC's Lord Dominiks, turning that 300 armor into 195 armor. Look, if Riot is gonna make ADC's be able to kill tanks again, then just buff a few of the many defensive armor items. For example:
: +50 Armor and 400 Health - UNIQUE Passive: Take 35% less critical strike damage taken from basic attacks,
: +100 Armor and 200 Health UNIQUE Passive: Reflect 25 (+20% Bonus Armor) magic damage when hit by a basic attack
: +70 Armor and +450 Health