Autumn is my second favorite season, just behind winter, because it ends the oppressive heat and humidity of summer. I finally get to wear jackets and sweaters without dying (because I do that in summer too :P), everything's comfy outside and inside, the leaves are changing, and Halloween is right around the corner. Note that around here, late September usually has the tail end of Summer's weather, so all of this applies more to October, but hey, it's the thought that counts.
The spring equinox is usually soggy or snowy, the latter of which is greatly preferred.