What do you mean by the most emotional? I think that every good song conveys emotion.
Kyrie Eleison by Mozart elicits powerful feelings of spiritual awe and wonder.
Moonlight Sonata by Beethoven elicits a great sense of melancholy.
1777 by Russian Circles gives me a sense of peace.
Ode to Joy by Beethoven makes me feel, and there should be no surprise with this one, joy.
There are so many songs that bring out strong emotions in me that I won't waste my time listing them. If a song does its job it will move you emotionally.
This particular song lulls along seemingly uneventful until it begins to approach the solo where it suddenly just grabs hold and I can't help but feel it deep in my chest. Most solos in songs seem to be there just to show off instrumental prowess but Billy Corgan knows how to turn this into something that draws a powerful emotional response.
Ultimately I think the idea of ONE song being more emotional than all others is ridiculous.