Quartz
Hero
Dex is pretty much the uber-stat at the moment. So how about reducing MAD and letting the fighting classes allow substitution? Thematically this is to fit the filmic travelling troupe of adventurers. They're not all Dex-machines. And see Your Highness for why you don't adventure in full plate.
Low level:
Fighter: may substitute Proficiency Bonus for Dex mod when calculating AC.
Paladin: may substitute Cha mod for Dex mod when calculating AC.
Ranger: may substitute Wis mod for Dex mod when calculating AC.
Medium level:
As above for Initiative.
High level:
Bring on the ideas!
This would mean that a lower-level PC would still benefit from full plate and medium armour, while a high-level PC gets an AC no better than plate (AC 12 armour + +6 PB) but still has some armour for when she's surprised. And a more experienced combatant is surprised less often. Dex still has all its other uses - in particular finesse weapons.
Low level:
Fighter: may substitute Proficiency Bonus for Dex mod when calculating AC.
Paladin: may substitute Cha mod for Dex mod when calculating AC.
Ranger: may substitute Wis mod for Dex mod when calculating AC.
Medium level:
As above for Initiative.
High level:
Bring on the ideas!
This would mean that a lower-level PC would still benefit from full plate and medium armour, while a high-level PC gets an AC no better than plate (AC 12 armour + +6 PB) but still has some armour for when she's surprised. And a more experienced combatant is surprised less often. Dex still has all its other uses - in particular finesse weapons.