Great points in this thread overall. The short answer is 2H and DW have different strengths and there's not a best answer. It depends on how you play and what you do most as to which is better. You also should consider what is more 'fun' overall.
DW play involves a lot more key presses per second, since overpower refreshes very quickly and you need to spam battle rage to keep fury below cap. The play style is 'death by a thousand cuts.' You kill stuff with a flurry of blows and WotB can be maintained at lower MP than a Skorn setup of equal dps. You get so used to playing with WotB up that you base your survivability off of perma-wrath play. So when WotB falls, you usually will die very quickly - having lost the dps boost, dodge, and move speed.
2H is much slower overall and you do not spam skills as much. You also are forced into higher MP to maintain WotB with WW and HotA builds. Perm-WotB is not so easy to maintain with low IAS, so you will make gear decisions based on surviving without the buff, since a fair amount of time at mid/lower MP can be spent with WotB down. But, rend only gains 10% cc from WotB, and as it does a lot of your AoE damage as a 2H barb, loss of WotB is not a big deal until you face elites with crowd control affixes. It's annoying when you lose WotB, but your dps and life stolen per second does not plummet like it does for a DW/WW barb.
If you love the rend skill and killing stuff in one hit, go 2H barb. If you love frantic action and killing stuff with a flurry of blows, go DW barb. I moved to Skorn not for efficiency, but for something different vs DW. It immediately felt less stressful and less 'spammy.' You can farm just as fast as a dual wield barb, but only if you are using rend in your build. However, it turns out 2H WW is the highest dps output for farming trash monsters at high MP.
The "tdps" stat of DW vs. Skorn will almost always favor the DW setup. But it is not a complete picture of dps for doing AOE damage to a pack of whites. If you are trying to WW down an elite pack, the tdps stat will give a fair representation of in game dps, simply because you are always on that elite target, hitting with ww/sprint. If your focus is elite kills with a Skorn, you will have better results against elites with HotA.
If you are looking to clear masses of trash monsters in single pass fashion, "tdps" is not a complete picture of what is happening, and rend damage needs to be included. If I WW through a monster, after casting rend, the damage that monster sees is usually 3 seconds of stumbling inside 1 tornado, 2 ticks of WW before I am out of range, and 5 seconds of rend damage --
At 1.82 aps (ias skorn + 41% ias), you get 18 hits with a tornado at 20% damage each, 2 hits at 48.3% from WW, and then 700% bleed over 5 seconds.
Tornado: 18 x 20% = 360% weapon damage over 3 seconds
WW: 145% x 2/3 = 97% weapon damage
Rend: 700% weapon damage over 5 seconds
Total: 1157% weapon damage dealt to monster
Say you are at 26/30 ticks breakpoint (EF mainhand and sword offhand stat stick). You may hit a monster 4x with WW, one tornado for 3 seconds and one rend. WW alternates hands, but assume the sword is a stat stick with 80% the average damage of the EF.
Tornado: (30+26 ticks)/2 x 20% = 560% EF weapon damage over 3 seconds
WW: 145%/3 x (2 hits with main hand, 2 hits with offhand) = 174% EF weapon damage
Rend: 700% weapon damage over 5 seconds
Total: 1434% weapon damage dealt.
So, in the comparison above, assuming identical critical hit damage, cc, and strength, a 1350 average damage Skorn (1485 dps, 1.10 aps) would do the same trash monster dps as a 1090 average damage EF mace (1570 dps at 1.44 aps). The offhand at 80% damage of the EF mainhand would have listed dps of 1221 at 1.4 aps...
This is exactly my point. However at the highest level you can get a 1300 EF with 90% crit and a socket. You can also Rend with an EF. So I think in the mid-tier Skorn is pretty good and can win in mp10 situations but at the top 10% it loses out as you get the better EFs.