In my experience before and during Covid, the Marriott Nanshan is a much better hotel in Shenzhen with an excellent lounge service and certainly better than the St. Regis with its rather poor elite offering in the evening and some erratic service issues.

The W Guangzhou was actually my go-to hotel there as it is one of the few Ws that has an executive lounge with free booze in the evening and they were very generous with the suite upgrades. I'm not a fan of Ws generally but the lounge, suites, and spa made up for the nightclub vibe in the lobby.