I’ll be in Beijing later this week and will be able to make a comparison. I loved Shanghai during my TWOV last year - it inspired me to get that visa - now, I’ve been to Shenzhen, Guangzhou, Chongqing, and am sitting in Chengdu right now.
If you’re staying more than 24 hours, definitely stay in the city.
All of the panda art work everywhere is making me like Chengdu the best ;-)