That was for the fifth faction though, it's not an indication of if they want to play as them instead of the 4 that were already included, all that vote showed is the community likes Alpha Legion vastly more than Red Corsairs or Crimson Slaughter. I'm asking if you saw a vote that compares numbers of the 5 included Legions. I recall only 1 such vote abd not very many people actually responded to it.
Plus the fact that all the Ork, Eldar and SM fans (many of the who might not even play Chaos) and ofc those Chaos fans that already have their own legion in voted in that poll. So basing the population size of Alpha Legion from the actual 5th subfaction vote is not gonna yield you any legit results.
Of course there is a measure of personal bias here, but Iron Warriors. Provided our player base sticks true to the nature of the legion in general, I see a force of "fight through the worst, never break, never sway" ironclad warriors with a purpose in wrenching control of strongholds from any foe that dares to deny us. All you other panzies always had us working the down and dirty jobs in warfare anyways. We've got 10,000 years of dirt, blood and hatred under our nails. Pragmatism will prevail where fanaticism has failed.
It's obvious that the Sorcerer's of the Thousand Sons will punish all who stand in our way. (that and magic ftw?)
If we are only counting those involved for the moment, I would personally have to argue in favour of the Black Legion. While there's certainly nothing wrong with any one of these forces, the Legion itself has a number of factors working in its favour. Along with retaining elements from multiple other groups and warbands, giving it a broader and more versatile pool of warriors to call upon than many of its counterparts, their tactics of beheading an army with rapid strikes would serve them well against most foes arrayed against them here. We are talking about a force which has trained for ten thousand years to pick out the chain of command within an army and annihilate it rapidly upon arrival after all, and given the loyalist astartes' reliance upon Apothecaries, the eldar reliance upon highly specialised units and the orks need for a domineering personality, it seems this would give them a major edge. The other factor to consider is that, of all those involved, the Black Legion is one of those still truly living up to its name. They tend to have the firepower, resources and ships of a full Legion compliment with fewer gaps in their units. Whereas the Word Bearers are more reliant upon hordes of cultists and daemons combined with massed infantry attacks, the Black Legion has been shown to retain a large number of vehicles, transports and assault tanks to compliment its forces. While this is certainly true of the Iron Warriors as well, the Black Legion's infantry tends to be better augmented with possessed and their ties to the Dark Mechanicus tends to offer them more frequent access to Titan support and the like. While it might not excel in possession, dark summonings or armoured units as the others, it occupies a nice middle-ground which provides solid support from both.
Ah yeah, from a strictly lore perspective there isn't a Legion that will be able to do something strictly better then the Black Legion until the mono-god armies join. And even then, there's something to be said for sheer numbers.
Well, in fairness, I could see the Red Corsairs doing a solid job as well. The problem is that most of their tactics tend to be reliant upon vessels above all else, and are more focused upon "smash and grab" jobs than prolonged campaigns. Then again, if anyone on the Chaos side could claim orbital supremacy or even draw away three enemy fleets at once, it would be Huron.