I too am having trouble pinning down to a certain team, in the past I've hopped from team to team, right now I'm with the Crew, because of Brain McBride, being that he was recently an Everton player. For those who are having trouble getting behind one certain team, I realize there are many way in which people reach a decision, through fav players, location and so on. If none of these are working for you, but you still want a team to pull for, then I suggest you choose a team, who you think will win the MLS based on your soccer knowledge, and follow that team for this season, and if that team grows on you, then there is your team, if not do the same next season too, eventually, something has to stick. The idea is just the same as what I always do if 2 teams are playing that I really have no interest in, I choose one for the day, and hope they win, for a little extra interest, the above is just an extension of this for a whole season.
Stick with Columbus, man. I think that team deserves the most respect because of their players. But that's just me.