Mine is Autumn, mostly because it's a season of change. School starts and the leaves change colors. Everything can start anew. It's a transition time between Summer and Winter where the weather isn't that bad (well, until you get to the end of November....). Most people see Spring as the season of rebirth and renewal, but for me, it's Autumn. Also, the translation of my middle name means Autumn!
Another question: "autumn" or "fall"?