PVG - this is my favourite city in China. Well except for HGK.
Yes, PEK has the Forbidden Palace and access to the Great Wall but the air quality is so bad I try and avoid PEK (as do many Chinese - they are paid are premium to work in Beijing vs rest of China). I have done both cultural visits, although I actually hired a guide to take me four hours outside Beijing to hike the Great Wall for four hours and there as there are far fewer tourists the further out of Beijing you get (in terms of the Great Wall).
PVG is a wonderful modern city and you if you can get out to the old water town - Venice of China, it is well worth the visit.