CEO of Storj here. You can sign up to use Storj and get the tools working to upload/download your files in 60 seconds. Last time I tried to use S3 it was 12 steps, and a phone call. Its faster, more secure, 50% cheaper than traditional cloud storage.

Basics are data stored for each. Storj: ~1400 TB, Sia: ~100 TB, Filecoin: Not Functional, Maidsafe: Not Functional.