Instead of reducing all damage by 30% and Instead of reducing damage by 5 damage per projectile up to 50%
Armor should be a hybrid of the two. It should reduce damage by 25-50% depending on how much damage the projectile is dealing.
For small damage projectiles like Tracer/Reaper/Sombra it should reduce damage by up to 50% like it does now. For burst damage like Cassidy/Pharah/Junkrat/Hanzo it should reduce damage by 25%
That way armor protects against all sorts of damage, and bursting tanks with armor is hard no matter what weapon is used. Then reduce/adjust how much armor all tanks have so its not broken when they have 300
This should smooth out how it feels to get shot at as a tank, with no crazy spikes from any source. Then once your armor is gone it is what it is taking full damage like everyone else