Obviously, this is my opinion, and readers are welcome to have their own opinions. But basically, I look at these factors: is the team a rival? Are they in a big market? Have the won the World Series more recently than the Diamondbacks? Would their fans become even more insufferable?
That said, I’m going to make the best argument I can make (in good conscience) for each team as well. Also, while it should go without saying, this is only for Diamondbacks fans, so if you’re a fan of one of the teams listed here, obviously you’re going to root for your team.