Horizontal vs. Vertical

Over the past several months, I have made it a priority to at least have SOMETHING to take away from every single session that I have done.  Whether it is a wedding or a portrait session, or even when I'm leisurely shooting landscapes of some sort.  I have to at least learn something.

Well, while I'm editing this most recent shoot of my friend, Laura, I have noticed that a mass majority of my shots are vertical.  While I do find that most of my favorite portrait shots are those that I've shot vertical, I've noticed in this case of how much of a significant difference in composition quality and expression of emotion an image has just by changing the way that it is shot. I don't know why I've never really thought about it before.  

I know that this probably won't always have such a significant difference in all of my sessions, but this one is where I've noticed it the most. 


These two images were shot by the same angle and in the same identical pose (the second one is just slightly closer).  In my opinion, I really do believe that the vertical image stands out so much more than the horizontal.  


What are your thoughts?