I would've thought they'd have the largest p2p size but Orks should be biggest

Oh my Asuryan. xD

In the Lore, they are the biggest of the four factions. But this is a game and it's really up to the players which army is bigger then the other.

It's not gonna be even close, maybe with the f2p players the orks will have the same pop as CSM, maybe.

We could literally keep on speculating, besides I think we have kind of gone off the main topic of this thread?

You're severely underestimating the amount of free to play players.

I was thinking more of the fact they're all free players have.

There are a lot of free to players, but how many of them are willing to play as an ork? Not many, at least in my opinion, I don't think there will be many wanting to play as a ork.

They don't have a choice. If they want to play the game for free, they play as an Ork or they don't play the game.

Or they could just buy the game and play as another faction...
Besides, the free to play option is limited (or at least from what I read it is limited) eventually they'll probably want to try a different faction...