External Storage i.e., portable hard-drive or Laptop

Fully user controlled, can be encrypted, portable, and not accessible by others without physical access

Easily lost, vulnerable to damage, no extra copy, only as safe as the circumstances

Cloud backed service i.e., Google Drive or Dropbox

User friendly, accessible from anywhere, interactive use of native files, shareable, sync-able

Possibly costly and subject to unexpected terms of service changes, potentially unauthorized access