I use TypeScript because the tooling is more mature (the decision to discontinue TSLint in favor of moving all its checks to ESLint is a thoughtful and mature decision), there's a ton of examples and tutorials for it, and it just generally seems to be where the industry is headed. Flow (JS) is a fine tool, but it just hasn't seen the uptake that TS has, and as a result is lacking a lot of the nicer small things, like thorough Visual Studio Code integration, offered by TS.
We chose Angular 2+ because our product has a rather complex back-office, most of which is visible only to our employees and contractors.
The "full featured" approach of Angular as well as the way it deals with the data model suited this business case well. We also use the Reactive Forms module a lot, as well as Clarity (an Open Source design system by VMWare) for the internal parts of the product. We also intend to use Angular's offline features.
For user-facing parts of the product we are now considering implementing views as Web Components with Stencil. We use Sass (SCSS syntax) for styling and TSLint to enforce a style guide close to Angular's default.