I thought it would more likely be the stylish one as he gets the most attention so would be under the most pressure or the one with badger hair as he seems to not be comfortable with fame. what makes you say him?
Honestly, it could be anyone of them. 2 of them have tried to quit Twitter, and have not been allowed. Their insane fans have actually harassed their families/girlfriends etc IRL. The stylish one seem most at ease, and just does his thing, but 2-3 of the others could easily be seen as being quite upset/stressed out.