There are a lot of different options when it comes to communicating with SharePoint. Here's som advice when to use them when building Apps:
See http://msdn.microsoft.com/en-us/library/jj164060(v=office.15).aspx for more general guidelines concerning client API choices and solution development. See http://social.technet.microsoft.com/wiki/contents/articles/12438.sharepoint-2013-best-practices.aspx for an overview of SharePoint 2013 Best Practices
Margriet Bruggeman edited Revision 2. Comment: add
Margriet Bruggeman edited Revision 1. Comment: add
Margriet Bruggeman edited Original. Comment: add