Microsoft can offer fully-integrated solutions with their already incredibly popular software. So that's a distinct advantage.
AzureAD is not Active Directory, and unless something has changed a lot in the last year (maybe it has?), Azure does not offer anything that looks, smells, and feels like on-prem AD in the cloud.
https://docs.microsoft.com/en-us/azure/active-directory-doma...
AWS has straight up guides for do's/dont's, and various ways to integrate their AD service with yours, including multiple scenarios such as running them as the masters of the forest, with read-only's on-site, and vice-versa.