Dude,Most of players like u (stack armor)are sh1t at tanking or never been tankin , i think ur never been tanking, or boosted by raid or good healers(no insult)? its simple
Pala avoidance- avoid + hp 45k hit to avoid it(exaple fester at 8 stacks some bosses do less like 20-25k per hit), simple paladins need much more avoidance coz they dnt have self healing or huge hp.
Dk full armor and hp coz they can self heal and u need to reduce dmg at full,pestilence glyph and u can self heal every time so if boss hits u 47k dmg (festergut at 8 stacks)hc u can instantly heal urself for 20k hp and u wont get killed by next hit including will of necropolis. So armor on dk is very important.
Druid tank also needs armor and stamina coz of huge health and unless like dk u depend on healers u can have 90k hp but u cant heal like dk.
So lets think on prot paladin to do 1% less dmg redution or to avoid 47k dmg by 7%.Idk its ur choice but i choose avoidance on paladin.
Mercy no insult dude but i think ur dps that think armor is best option for prot pala.First do tanking then u will see my option is better than noobs that say armor is best.You will see,after all blizzard employers know better than you,and they are right in every cause.In the end i did test ur full armor Pala and guess wut,2x times i triggered ardent defender which never happened, with my avoidance set on fester hc b4.