This is a little silly considering that they haven't played each other yet, but it is interesting to see how this rivalry is already building up. I would guess that in a few years it will be the #1 rivalry in MLS.
http://www.mlssoccer.com/news/article/2015/03/03/mls-rivalry-power-rankings-top-10-rivalries-mls-voted-fans
http://www.mlssoccer.com/news/article/2015/03/03/mls-rivalry-power-rankings-top-10-rivalries-mls-voted-fans