S3 became strongly consistent only recently (https://aws.amazon.com/blogs/aws/amazon-s3-update-strong-read-after-write-consistency/ https://aws.amazon.com/blogs

S3 became strongly consistent only recently (https://aws.amazon.com/blogs/aws/amazon-s3-update-strong-read-after-write-consistency/ https://aws.amazon.com/blogs/aws/amazon-s3-update-strong-rea...) while I think GCS and Azure Blob Storage has strong read-after-write consistency for a while now. In any case, Cloud Spanner provides strong consistency in multi-region deployments.