Assuming you are comfortable with JavaScript and its weird parts, I will break your question into several smaller ones:
- Backend Framework - I wouldn't call it backend framework, but Node.js framework. Loopback provide great structure for your code and help you quickly generate your API. It's build on top of Express, so you can use Express routing. If your project become large, Express can become burdensome. That said I would still vote for Express - it's mature, it's the most widely used framework out there, so finding solutions to potential problems will be much easier. You are still learning, so you will need all the help you can get!
- Template engine - this totally depends on the projects you will be building. There is a great tool called Template Chooser - although depricated, you can still get an overview on what engine to choose. I'm a big fan of EJS, because of the performance it provides compared to others.
- Front-End Framework - again, depends on your current needs. ReactJS is a great front-end framework and it's gaining popularity really fast. Vue is also great, though I haven't got a chance to try it still. But there are other frameworks like Backbone, AngularJS, Ember, Mithril etc. You can check Addy Osmani's article about Journey Through The JavaScript MVC Jungle (it's 3 years old but it is a great read!!). You can read John Hannah's article Choosing the Right JavaScript Framework for the Job too.
- Development Tools - Gulp! You can check Grunt if you want, but few have changed their minds to use Grunt once they've tried Gulp. About Webpack vs Browserify - they serve different purposes. Browserify was build, so you can use your Node code in the browser. Browserify pushes all features that don’t fit into it’s philosophy of running Node code in the browser into transforms and plug-ins. This assumes you are only using it in NodeJS projects. Webpack was build from the ground up and helps you manage your static front-end assets. In my honest opinion, you should try them and learn to use them both!
- "If i want use ES6, is it must to use babel in the backend?" - I don't really understand this question. If you ask "Should I use ES6 with Babel?", the answer is yes. Babel is a transpiler, which compiles your ES6 code to a working ES5 equivalent, which you can use today in your project. Currently Babel is the tool with the best ES6 feature support.
- Is there a stack I miss? - Learn about NoSQL and database management, Testing and TDD, Continuous Integration and Continuous Deployment, TypeScript is also something that can intrigue you.
Keep in mind that all of the above wouldn't matter if you don't have a solid understanding of JavaScript!