I prefer frameworks that focus on pure javascript because the ones that don't tend to allow you too use javascript but have sparse documentation on how to use it effectively, instead focusing on typescript. When I first tried Angular 2 their javascript "hello world" example wouldn't even work, it was some bug in their site. I already need to use all sorts of other tools and abstraction layers when building websites/apps, typescript feels like just another abstraction layer (which it is), that means another vim plugin for typescript (or a bloated IDE), another npm dev dependency, another layer to the build process, so I try to avoid it for these reasons.