how to use ng-option to set default value of select element

So assuming that object is in your scope:

<div ng-controller="MyCtrl">
  <select ng-model="prop.value" ng-options="v for v in prop.values">
  </select>
</div>

function MyCtrl($scope) {
  $scope.prop = {
    "type": "select", 
    "name": "Service",
    "value": "Service 3", 
    "values": [ "Service 1", "Service 2", "Service 3", "Service 4"] 
  };
}

Working Plunkr: http://plnkr.co/edit/wTRXZYEPrZJRizEltQ2g

The angular documentation for select* does not answer this question explicitly, but it is there. If you look at the script.js, you will see this:

function MyCntrl($scope) {
  $scope.colors = [
    {name:'black', shade:'dark'},
    {name:'white', shade:'light'},
    {name:'red', shade:'dark'},
    {name:'blue', shade:'dark'},
    {name:'yellow', shade:'light'}
  ];
  $scope.color = $scope.colors[2]; // Default the color to red
}

This is the html:

<select ng-model="color" ng-options="c.name for c in colors"></select>

This seems to be a more obvious way of defaulting a selected value on an <select> with ng-options. Also it will work if you have different label/values.

* This is from Angular 1.2.7

This answer is more usefull when you are bringing data from a DB, make modifications and then persist the changes.

 <select  ng-options="opt.id as opt.name for opt in users" ng-model="selectedUser"></select>

Check the example here:

http://plnkr.co/edit/HrT5vUMJOtP9esGngbIV

<select name='partyid' id="partyid" class='span3'>
<option value=''>Select Party</option>
<option ng-repeat="item in partyName" value="{{item._id}}" ng-selected="obj.partyname == item.partyname">{{item.partyname}}
</option>
</select>