HP and armor runes need buffs.

80 HP at level 18 feels worthless when you consider has 776 more HP than at level 18.

On the other hand, armor is already the least useful stat in the game. 6 armor might be slightly useful at the first minutes of the game but becomes worthless as the game progresses like the armor items while 8 MR is always useful if the enemy team has AP champion (otherwise it's worthless too). Enemy is going to one shot you or is going to kill you in 3 auto attacks anyway. Some people pick 6 armor rune over 8 MR rune just because AP champions are rarely played.