It's hard to understate this point. Compared with San Francisco, Pittsburgh is much more visibly green. There are trees everywhere, grassy areas abound, and the city itself is nestled in green hills.
San Francisco is full of concrete. The Bay Area is still really brown from the recent droughts. There are certainly people who can overlook this and live perfectly contently. But in Pittsburgh, I don't have to give up the greenery for a city life.