JSFiddle - React, Tailwind, and code Playground

HTML

<script src="//cdnjs.cloudflare.com/ajax/libs/angular.js/1.4.5/angular.js"></script>
<div ng-app="myApp" ng-controller="demoCtrl">
    
    <select ng-model="selectedKey" ng-options="obj.Key as obj.Key for obj in list">
      <option value="">test</option>
    </select>
    <div>Выбор: {{selectedKey}}</div>
</div>

JavaScript

var app = angular.module('myApp', []);

app.controller('demoCtrl', function ($scope) {
   $scope.list = [
       {'Key': 'key1', Value: 'val1'},
       {'Key': 'key2', Value: 'val2'},
       {'Key': 'key3', Value: 'val3'},
       {'Key': 'key4', Value: 'val4'}
   ];
});