I myself would like to cast a ballot in favor of the hypothesis 6.
That is, I think that the electron is a mathematical point mass and at the same time a point charge having infinitesimal size. Also, concerning to other elementary particles, I think that I must regard all of them to be infinitesimal points.
Think a hydrogen atom.
If the electron and the proton have finite size, then they will collide with each other someday, and this collision will jepardize the stable eigenstate they are leading when they collide with each pther. Then the forever stable eigenstate of the hydrogen atom will never be possible, Sirs!
If they are mathematical points, this difficulty can be avoided.
And our harmonic view of the hydrogen atom can resume its peace.