Coming from Boston (and then returning to Boston), my favorite part of Seattle was the weather. It was so mild all the time, didn't need to think about it (except the one week in the summer everyone would melt because nobody had A/C).
Same. I lived in Chicago and NYC before living in Seattle for a couple years and found the weather to be gorgeous almost year round. Weather-wise it was significantly better than both.
Lots of sun and plenty clear days and so much to do and see when the weather was right. When it did rain it was just a little mist or the occasional drizzle.
What's funny is that every time I see Seattle in a movie or tv show, it's constantly pouring. Weather I've almost never seen there for longer than a couple hours.