REST Services vs WCF Data Services for Sharepoint 2013 CRUD function for external systems

Question

Need expert opinion about using REST services VS WFC data services for SharePoint List CRUD operations for external systems with respect to

1. Authentication (with in intranet and externally),
2. Uploading multiple attachments,
3. Document CRUD operation for SP library.

Answer 1

Rest (_api) is preferred over WCF wherever possible in SharePoint 2013

For Authentication, there is a restful way of doing this - check out this and this discussion

Check out the MSDN reference around CRUD operations with Files and Folder

Source