Operations needs to migrate 10 TB from a third-party object storage to Cloud Storage quickly and cost-effectively following Google best practices. Which method should they use?

Storage Transfer Service is the most appropriate solution for migrating 10 TB from a third-party object storage to Cloud Storage. It is designed for large-scale, online data transfers, offering features like data integrity checks, transfer scheduling, and bandwidth optimization, making it both quick and cost-effective. Using gsutil mv is suitable for smaller transfers or transfers between Cloud Storage buckets, but less efficient for 10 TB from a third-party source. Transfer Appliance is for extremely large datasets (petabytes) or situations with limited network connectivity, which isn't specified here. Downloading data to on-premises storage and then re-uploading introduces an unnecessary intermediate step, increasing time, cost, and potential for errors.