What is best practice to create an AngularJS 1.5 component in Typescript?

If you wanted to completely adopt an Angular 2 approach, you could use:

module.ts

import { MyComponent } from './MyComponent';

angular.module('myModule', [])
  .component('myComponent', MyComponent);

MyComponent.ts

import { Component } from './decorators';

@Component({
  bindings: {
    prop: '<'
  },
  template: '<p>{{$ctrl.prop}}</p>'
})
export class MyComponent {

   prop: string;

   constructor(private $q: ng.IQService) {}

   $onInit() {
     // do something with this.prop or this.$q upon initialization
   }
}

decorators.ts

/// <reference path="../typings/angularjs/angular.d.ts" />

export const Component = (options: ng.IComponentOptions) => {
  return controller => angular.extend(options, { controller });
};