Determine file storage strategy in API

We need to determine how uploaded files are stored by the API.
Some initial thoughts, input welcome:
- API receives the file, submits the hash to protocol
- pulls any metadata/mime-types from the file
- creates a thumbnail image --> sends to public S3 bucket for discoverability
- in dynamodb: store mime-type, S3 URL, hash, thumbnail path, file size (bytes), metadata provided by supply user
- should we store this in S3? Or should it be a local file system to the API...?
- S3 Pros:
- S3 is cheap and can easily be used as a CDN source
- delivery payload can be a signed URL with expiration
- S3 Cons:
- S3 is slow as a file system
- File system pros:
- fast 🐇
- File system cons:
- syncing with CDN can be a pain
- need multiple file systems or shared file system for supporting highly available API instances
- this rules out ECS Fargate. We'd either build on EC2 or EC2 based ECS