Angular $http vs service vs ngResource

Decided I’ll formulate this into an answer since in the comments we worked out basically what you wanted to know:

Using $http or $resource the results can still be cached, you pointed out the reasons to use one over the other really in your question. If you have a RESTful interface then using $resource is better since you’ll end up writing less boiler-plate code that is common to a RESTful interface, if you’re not using a RESTful service then $http makes more sense. You can cache data either way http://www.pseudobry.com/power-up-http-with-caching/

I think putting $http or $resource requests into a service just generally works out better because you want to have access to the data from multiple locations and the service acts as a singleton. So, basically you can handle any kind of caching you want to do there and controllers can all just watch the appropriate services to update their own data. I’ve found that a combo of $watch in the controllers for data on the service and returning the promises from my service’s methods gives me the most flexibility with how to update things in the controller.

I’d put something like this in my controller having the exampleService injected at the top of the controller definition.

angular.module("exampleApp", []).service('exampleService', ["$http", "$q" ,function ($http, $q) {
    var service = {
        returnedData: [],
        dataLoaded:{},
        getData = function(forceRefresh)
        {
            var deferred = $q.defer();

            if(!service.dataLoaded.genericData || forceRefresh)
            {
                $http.get("php/getSomeData.php").success(function(data){
                    //service.returnedData = data;
                    //As Mark mentions in the comments below the line above could be replaced by
                    angular.copy(data, service.returnedData);
                    //if the intention of the watch is just to update the data
                    //in which case the watch is unnecessary and data can
                    //be passed directly from the service to the controller
                    service.dataLoaded.genericData = true;
                    deferred.resolve(service.returnedData);
                });
            }
            else
            {
                deferred.resolve(service.returnedData);
            }

            return deferred.promise;
        },
        addSomeData:function(someDataToAdd)
        {
            $http.post("php/addSomeData.php", someDataToAdd).success(function(data){
                service.getData(true);
            });
        }
    };
    service.getData();
    return service;
}]).controller("ExampleCtrl", ["$scope", "exampleService", function($scope, exampleService){
  //$scope.$watch(function() {return exampleService.returnedData}, function(returnedData){
  //  $scope.myModel.someData = returnedData;
  //});
  //if not using angular.copy() in service just use watch above
  $scope.myModel.someData = exampleService.returnedData;
}]);

Also here’s a nice video from the Angular team on Best Practices that I’m still re-watching and slowly absorbing over time.

http://www.youtube.com/watch?v=ZhfUv0spHCY

Specifically on services vs controllers:
http://www.youtube.com/watch?v=ZhfUv0spHCY&t=26m41s