I think, based on evidence, that the Toru Hagakure = the traitor theory is most plausible.
However, I believe Horikoshi himself mentioned that he completely forgot about the traitor plotline. So I think he might go with something different than what he had in mind initially when he started the traitor plot.
The thing is, I think the traitor plotline is interesting, because ever since it was introduced I kept it in the back of my mind. But I am really hoping that whoever it is, it is someone impactful. While I think Toru is logically the most plausible traitor, I don't think her being the traitor is very interesting. I would much rather have someone like Ochaco be the traitor (that would be super interesting), or Tsuyu, or Momo. Someone who has had attention in the story, someone we as the readers have followed pretty closely and think we know, so someone that was the traitor right under our noses.