They're all the same quality. Sometimes great, sometimes terrible, but will get the job done as long as you put in the effort. Also bigger customers will obviously get more.

GCP does win on pricing now with role-based support that is a flat rate per user: https://cloud.google.com/support/role-based/

As someone considering GCP, could you relate a story or two about GCP support’s technical competence specifically?

It appears not since 2011, according to the information sources you would have looked through.