The TFS Default Build Process Template Extension for Visual Studio 2013 and Team Explorer 2013 allows you to update the default build process template used when creating a new build definition.
Download this extension now at https://visualstudiogallery.msdn.microsoft.com/86a239cf-b0e3-4af4-a6a2-319b135867c0
To use this extension, open your Build page of Team Explorer 2013, expand the Section named “Default Build Definition Template”, right-click a build definition template, select “Set as Default”. The extension will update the select template to be the default when creating future build definitions.