its always a hard one to answer, I love summer when I can get out on the water, be it sailing or wakeboarding, and for getting back on my bike (definitely a fair weather cyclist) but I struggle with the heat, at least my new just is in an air conditioned office and not in a non air conditioned kitchen . . . but even at night, trying to sleep I struggle with the heat.
So with that I love winter, I like being cold, I sleep better when its cold, but it sucks for my summer sports =p and living in a little village if/when it snows we often get snowed in, and my car isn't best suited for snow driving, so I have to walk to work which takes an hour or two, depending on the snow =p
Autumn and spring are a bit wishy washy for my liking, can never make up their minds etc =p