Well MrBoJangles, I can only speak from a Barb's perspective and to run MP10, I would suggest the following:
Helm: Mempo of Twighlight with 250+ Strength, 6% Critical Hit Chance and a Socket.
Shoulders: Vile Ward or rare with = stats with Strength 250+, Vitality 150+ or mix of Vitality and Life %. Also all resist 70+!
Chest: Immortal King's Eternal Reign with 150+ strenght and 200+ vitality.
Bracers: Lacuni Prowlers with 100+ strength, 6% Critical Hit Chance, and make sure it's one with 9% attack speed and not 8%. Vitality is a bonus but not necessary.
Belt: The Witching Hour with 250+ Strength, 9% attack speed and not 8%, and at least 45% Critical Hit Damage.
Immortal King's Tribal Binding with 250+ Strength, 3% Life Conversion and vitality as a bonus. Extra bonus goes to one with bonus damage to whatever fury building attack you choose in your skill build.
Legs: Inna's Temperence with 90-100 Strength, 90-100 Vitality OR no strength and 170+ vitality. Make sure it's one with 9% attack speed and not 8%.
Boots: Ice Climbers with 250+ Strength, 100+ Vitality.
Gloves: Immortal Kings Irons or rare with = stats. In particular, if you end up using a witching hour belt, you should be more inclined go to with the Irons rather than just a rare in order to get the set bonus. You'll want strength with at least 8% attack speed, 8% critical hit chance and as high critical hit damage as possible keeping in mind that 50% is max. Vitality would be a bonus here.
Necklace: Anything with strength and hight attack speed, critical hit chance of at least 8% and critical hit damage of at least 80%. Vitality, damage bonus, and all resist are nice to haves as well.
Rings: Almost the same as your necklace except max Critical hit chance is 6% and max critical hit damage is 50%.
Weapons: You have two options. Either go with a 2 handed Skorn or two 1 handed weapons. If you have the Immortal Kings belt with Life Steal then you don't have to worry as much about having it on your weapons but if you have the witching hour, then you'll want to go with two weapons instead of the 2 handed Skorn. Your Skorn should have at least 300+ strength, either attack speed, Life Steal OR 150+ vitality, and at least 170% critical hit damage with a stocket.
If you go with two weapons, at least one should have life steal if not both, both NEED to have at least 80% Critical hit damage and a socket and both should have 150+ strength and vitality as a bonus. Lastly, at least one of those weapons will need to be a mace or an axe in your characters right hand to get the critical hit chance bonus from one of the bellow listed passive skills.
Your passive skills will need to be Ruthless and Weapon Master for the Critical hit chance bonuses and your third will most likely be blood thirst for the life steal.
As for your active skills, you can just google the various barb build options and pick what you want from what others are using. :) If you look at me, I'm using a WW skill build although right now my skills are based on low MP xp runs rather than MP10 uber boss runs hunting for Hellfire Ring ingredients.