It's too much of a generic question to be answered right. Do you need global availability? Do you need high speed downloads? Are you worried about bandwidth costs? etc.
We use S3 + Cloudfront for documents that we want to be quickly accessed by our customers. We use SFTP for our internal docs when we don't care that much about availability and speed.
We use S3 + Cloudfront for documents that we want to be quickly accessed by our customers. We use SFTP for our internal docs when we don't care that much about availability and speed.