Flammkin Barbarian Edit
I play with a Flammkin Barbarian mostly. I like to not to have to worry about molten and vampiric enemies. I throw two points into both vit and str so I can take and give a beating. Most of the game isn't that hard but sometimes you might need to grind in the last area or just have some luck.
Jim Bob's Barbarian Edit
I play with a (softcore, I'm a noob) Berserker Barbarian. I never have to worry about dying, because I put EVERY SINGLE POINT INTO VITALITY. I have 100,000+ health at level 120, I also put most of my skill points in Max Hit Points, and have 100 in it. The rest of the skill points I am now putting in Attack to try and get 100 attack. I fight monsters up to 20 levels higher than me and charge at bosses like a carefree mad-man. So, put everything in health and you will come out alive! Potatoes!
I also recommend putting points into Intelligence. 1 int is the equivalent of half a vit and half a str.
The Brainless Brawler Edit
Barbarians are a nice "beginner" class since you only need to worry about 2 stats for most of the game and are pretty easy to play. Here's a somewhat in-depth guide that focuses on survivability (since this is a game with permanent death, after all) but still isn't a slouch in the offense department.
Race: Huskian or Sonite, unless you have Grokarn. Huskian is a bit more aggressive while Sonite is more defensive. Grokarn is the best race for a barb IMO but you'll have to unlock it first!
Stats: Alternate between +3 VIT/+1 STR and +2 VIT/+2 STR at each level.
Mastery: Heavy (Axe/Polearm) for the huge bonus damage from STR and the bonus crit damage.
Passives: Pump HP to tier 4 or 5, then dump everything else into armor. The armor passive also gives higher block rate, and the diminishing returns on the HP passive make it less useful later on.
Personality: Adamant (+3 VIT, -2 DEX)
Discipline: Marauder. Boosts our block chances and restores HP after blocking. Since barbs also get +1% ATK until end of combat after blocking, this also indirectly boosts our offensive capabilities a bit.
Gearing: Stack VIT and STR. Some DEX is also useful for higher dodge and crit but not a priority. Use heavy armor and shields if at all possible for higher damage mitigation. However, higher block rate on a light or medium shield might be more useful than sticking with a heavy shield.
Combat: The tried-and-true rotation of "1 2 3 3" should honestly get you through most of the game, long as you remember to reposition and heal when necessary. Your hit confirms deal huge damage so use them whenever you can, plus they give you the chance to grapple. Use charge instead if your rage bar is full (glowing blue) since it can't miss and deals EVEN MORE massive damage. If enemy is guarding, use whirlwind to try and break instead of repositioning. If you get ensnared, use cleave. Using all these tips, you should be able to easily stack combo points for your ult for high damage output.
Bloodthrusty Barbarian Edit
This build focuses on the skill Bloodthrust, a very high VIT build and a self bleeding weapon (unstable, cursed, etc.) that makes you bleed frequently.
I currently have a lvl 236 Barb which I built with about 50/50 STR and VIT. At one point, I noticed that I could 1-3 shot monsters with Bloodthrust that would otherwise take many other attacks. For bosses that perma-bleed me, I only use Bloodthrust to attack.
Bloodthrust: Transfers all stacks of Bleed over to the enemy and deals your MAX HP as damage to the enemy. If you focus on high health, you will deal some insane damage - far more than you could achieve with STR.
AFTER you get your bleeding weapon, put all points into VIT and focus on getting VIT from gear when you can. Always choose Max Health option for skill points even for other builds, this pays off A LOT long term. I didn't realize this and wasted points in a bunch of other categories, but even still, I have 30% chance to heal 1/4 of my max health as my 236 Barb which drastically improves my survivability in fights.
This barbarian focuses on using the 'Reckoning' mantra, but is also able to use Bloodthrust and some of the other high VIT strategies above.
Race: This build is pretty race neutral, but It's probably best to pick a race that gives you the possibility of healing per turn or that has an ability that scales with VIT. Brauthir is a pretty good option since it should take a long enough time for even a boss to kill you which makes it likely even at 3% that you will get a full heal over the course of a battle. Vassian or Silian might be a little more consistent.
Stats: +4 VIT every time, first priority is to gear for as much VIT - although it's a good idea to have some extra INT and WIS just in case
Discipline: Marauder - this is why this is a barb build, the additional block chance and the heal while blocking is very strong
Passives: Armor (pretty much exclusively) we want to max our block chance, every additional percent chance to block is better than the last.
Weapon Proficiency: The simplest thing is Wand/Staff - the main thing about this is that it gives you reliable MP regen - equivalent to 300 WIS. The confuse (at mastery) is a nice addition. Again, since ATK isn't important it doesn't matter that we're not stacking INT. If you have enough WIS to consistently use riposte/barrier then you could probably use anything that's not a bow (since bows prevent you from blocking.)
Wardrobe: Lizard Garb - the extra 5% max HP per turn healing is a pretty big deal, adding additional shards to reduce the attack penalty is good but not a huge deal since your attack is not your main source of damage
Gearing: VIT is the main concern. It is nice to get equipment that heals you for 1% per round, or that damages the enemy for 1% of your HP per round. It can also be nice to get a self-bleeding weapon. Try to get heavy armor and a heavy shield, but the most important thing about the shield is the block chance.
Mantra: Recoking - this is your main source of damage
Early on, this is more or less a normal barb. Things change when you get recokning.
Begin most fights with reckoning, you can also cast barrier a few times while mantra is running for some additional mitigation. Once you get enough HP you should kill normal enemies in less than 10 turns of reckoning.
While reckoning is going, I ended up mainly using the 1 3 3 rotation since the 2 attack neither scales with VIT (like the 1 attacks do) nor does it heal. You can cast heal as much as you want, especially early on it can help you survive - but since some of your attacks heal you as well it's not so necessary. Since you are using a wand, you can spam reposte to clear conditions too (if you don't care about your barrier, that is.)
Be aware that reckoning doesn't work if you're blinded, so attempt to get rid of this condition as quickly as possible. Be aware that the final boss (infernal guardian) will perma-blind you making reckoning useless - but at the same time during this fight you also get a permanent bleeding condition - simply finish him off using bloodthrust instead.
This build was able to get me to new game+ with only a few close calls.