SFTP stands for 'SSH/Secure File Transfer Protocol'. SFTP is used for secure and fast file transfers, so it's perfect for uploading your content, especially if you're uploading in bulk. All data is securely transferred using a safe, private connection, so you can rest assured your content will be secure the whole time.
Also, SFTP allows you to resume any uploads that get interrupted – which is especially great if you are uploading large files.