Start with what you know, don't spend months figuring out a certain database tech for example when MySQL/mariaDB is just as good for 99% of the use cases.
I know there's a lot of bias out there against PHP. But I would still use it over the alternatives, there's a large community. With excellent frameworks who do the heavy lifting for you. (Symfony, Laravel). Great support and tooling, a large recruiting base and easy to pick up.
I personally love using Drupal 8 (which is built with Symfony), it has an excellent database abstraction layer, you can easily swap MySQL out for Postgres for example. There's a lot of functionality built in, and very developer minded (compared to WP) with many extra 3rd party addons. It also has a proven track record with deployments from small SMB to large enterprise users. It can also easily be extended with any Symfony packages.
For front end, I swear by Ember.js it is a framework which makes a lot of important decisions for you. You don't loose time setting up your tooling, deployments, state management, ... A great community, many excellent add-ons. A proven track record (LinkedIn, Twitch, Apple Music, ...)
And on top of that, it has been around for 6 years, and is still actively developed with regular releases, with a excellent deprecation support so you can easily upgrade to new versions.