Armor depends on your build. I'm level 98 melee with faith protection spells (22 Vit, 15 int, 40 end, 27 str, 28 dex, 10 magic, 24 faith, 12 luck), but use the black leather armor because it is super light and has one of the fastest stamina recharges of all the armors, which is something I need because I use the Meat Cleaver and Large Sword of Moonlight. I will try to sport King Doran's armor if I can hold it, but since Ostrava disappeared from my game I have to wait until NG+ to find out if I like it. I started out as a hunter with regular leather armor, and I went with something weaker and faster as the game progressed.
In short, I think a strong shield and powerful weapons are better than heavy armor.