As someone who has used very many "cloud providers" (including GCP, AWS, and Azure), it cannot be said that Azure is the most stable. GCP is far better for stability and reliability than Azure.

The extensive experience with Enterprise Authentication that the decades of use of Active Directory has given Microsoft may mean that their SSO and Enterprise Authentication stuff is the best out of those on offer. I wouldn't know about that... I just made (and destroyed) VMs and was often driven to frustration whenever Azure failed to reliably perform that simple task.