Jawww

Eaten in both cities extensively:

Chongqing: street food is unmatched. Little hot pots on Nanping Road. Every neighborhood has its own chaoshan. The food is aggressive and unapologetic.

Chengdu: more refined, more options. Mix of Sichuan classics with international influence is better here.

Winner for me: Chongqing. But Chengdu gets points for better craft beer scene.