What's your usage model? Lots of files, long tail? Very few files but very popular? Are the files really large (videos) or medium (images) or small (text)?

What's your usage model? Lots of files, long tail? Very few files but very popular? Are the files really large (videos) or medium (images) or small (text)? How much are you willing to spend? Do you care about latency or just throughput? Etc.