1. Weapon: Avoid 2h weps unless they have 400+ vitality and 1000+ loh and you only use it to do quick runs at mp0. Dual wielding is almost always inferior to sword and board. If you must dual wield, your weps need 200+ vitality and 500+ loh. Your two best weps, ehp wise are the empyrean spear and the doombringer. It's a choice between 70+ ar and 7% block. Try to get as much vitality as you can on the single random roll. High loh is another good option. If you can't afford either, get dex then for dodge chance or a split dex-str roll for more damage. Don't worry too much about super high wep damage, anything 600+ is good and 800+ is great!
2. Shield: This is mandatory for HC, for without a shield you are very badly gimping your ehp. Shields let you gain 1000+ more armor, 60+ more resist, tons of vitality and 20+ more block. This can add a 50% to 100% boost to your ehp, meaning you could have 2m ehp instead of only 1m! Stormshields are probably the best for all classes, especially barbs. Get as much block as you can then worry what type of random roll you'll get. Unless you are extremely rich, skip vit(or %) life in that slot. I went with the max of 34% block, it's great even with a weak random of cold res.
3. Helm: The best helm, ehp wise is without a doubt the helm of command. It's a must for all shield wearers. Mempos may seem good, but they can't touch helms of command ehp wise and they cost far, far, far more. 8% block is vastly better than 8% ias. If you need attack speed this badly, there's several other slots for this, but very few slots for block. You will want at least 2 good rolls on your helm of command. Sockets and ar are really expensive but you can look for extra vitality(split primary+vit roll), 200+ extra armor, % life rolls(partially makes up for socket), life regeneration, etc. Avoid helms of command with 0 or 1 good random rolls since they can roll 4 randoms. Don't be afraid to give up damage in this slot if you can find one with 3 or 4 good defensive randoms.
4. Rings: All resist is a must for those two slots. You also want either vitality or % life. Unless you are extremely rich, forget crit and attack speed because it's not worth gimping your ehp by getting more dps. Life on hit is also nice, but only if you can also have vit and ar along with it.
5. Amulet: I chose to get a high loh roll instead of all resist. For some reason, you give up alot if you want resist in this slot. I will be crafting vitality amulets and have a good chance of getting one better than what I have.
6. Boots: I have firewalkers which I will only be using on lower MP levels because it's missing vitality. For MP3, I spend more time fighting than running so I will be buying some rare boots with primary+vit+dex+ar and ill also try to get armor, life regen, health globes, pickup radius, etc.
(con't in next post)