Personally? Winter. I love the cold, and hate being hot, so, yeah. However winter costs me more than I am am ever willing to pay unless absolutely necessary, that being time, as traffic is slower and I need to prewarm my car. Plus, while both seasons have their own flavor of bullshit that comes into my work, I am generally much happier handling the messes that come with hot weather than with cold weather. So, summer.
winter, as a hot and cold thing. if you're cold, you can put on a bunch of layers and not be cold anymore, but if you're hot, you can be completely naked, and still be hot.