As a kid growing up in Tulsa, I was a Cardinal fan. I couldn't stand it that a sucky team like Detroit could possibly stay on the same field as Bob Gibson and the mighty Cardinals.
Living in Houston and not being a diehard MLB fan, I love watching the Astros. Since I am not emotionally invested, I can watch them good or bad. It's more about going to Minute Maid Park or setting on my patio in the spring/summer than it is about rooting for the home team.
Showing my age, when cable first came out and became affordable, I was a large Braves fan, purely because of the TBS Superstation and the ability to watch the same team every day. Plus the Braves were really good back then - Dale Murphy, Bob Horner, Pendleton, etc.