Boston or Seattle? Which wins for overall quality of life?

I have job offers in both cities. Moving from Bay Area. Which do you think is better overall?

Assume I have no pre-existing ties to either city. Please consider cost of living, arts and culture, job market, feel/look of city, climate, activities, travel opportunities, ease of entry into new social group, and traffic/commute. Google has a lot of info and opinions, but I trust the Fluther community more.

Go! :)