Over the years, the stack I use to develop software has steadily changed. Here's what I would gravitate towards these days:
I've been growing fonder of RxJS, so that would probably make it into the mix either way.
For testing, a combination of (Mocha || Jasmine || Chai) and Protractor.
Unless I had a dedicated designer who could produce clean HTML, Bootstrap would be my base styling layer.
This is a big tossup and would really depend on the project. Django/Python running in Docker containers is a solid choice for me due to familiarity and easy of getting started.
But a Serverless architecture could really be intriguing depending on the project parameters. I'm working on a little side-project right now using this since it will cost me essentially nothing to run it.
No matter what I did, the backend would mostly just be an API for the frontend to call, not a lot of pages would be served up.
Again, depends on the project. The MySql family (MySql/MariaDB/Aurora) is a solid choice that I have a lot of familiarity in. If the project warrants a relational DB, that's probably where I am. Postgresql is fine too.
But if the project has some unique needs, and a non-rel DB would be preferred, I'd probably go with DynamoDB to avoid any maintenance issues. I really like the idea of saying "I need XX read and XX write throughput" and having it magically happen as long as you give some small consideration to partition keys.