I'd strongly suggest using Webpack to build any new serious frontend projects. It's incredibly powerful and flexible enough to be able to adapt to any changes in the ecosystem without having to throw stuff away. As a data point, I know a large projects that slowly migrated away from AMD, favoring CommonJS, and later ES modules. Since ES modules are part of the standard, it makes sense to converge. This was achieved with comparably minimal effort, without throwing code away, and all while enabling newer code to be written in the modern style.
React is an incredibly safe bet as well. Facebook is so heavily invested in it that they have multiple engineers working on it full-time. Furthermore, since they actually use the framework, any breaking changes are required to have a clear migration path. They published a blog post [0] explaining their strategy for how they intend to handle version transitions, which I consider incredibly developer-friendly. Look at angular 1.x for an example of a horribly handled transition.
Don't bother with specific tech stacks, because as mentioned, the churn rate is really high. Instead, hire good problem solvers who you can tell from their interviews will be able to choose a framework that works well for your new projects, or adapt to the framework you've chosen yourself for your existing ones.
Understand that good programmers are kind of hard to find, but okay programmers with experience in XYZ stack are not. Why? Because any reasonably competent programmer can become familiar with a new framework or library in about a week or two. Being able to separate the signal from the noise, and architecture an application well within that framework? That's what you're looking for. The tools themselves aren't that important.
Of course, to follow this advice you have to be able to identify problem-solving ability, which is hard and why most hiring managers fall back on buzzword bingo--to say nothing of HR departments.
My approach with hiring is to try and find solid JavaScript programmers foremost. People with experience in the tech we use, or people with a lot of experience with other languages are nice to haves.
Anyone who has a solid grasp of (modern) JavaScript will be fine with any front end tech stack.
Well, I mean, sure... but, having hired all these random "solid JavaScript programmers", what do I tell them to use and/or learn? To do useful work, they all need to be using the same thing—so... how do I figure out what should be the standard for a project, if there's nothing forcing any particular option?
You can let them decide? Then follow agile principles to make sure they are delivering prototypes/features.
Ideally you would get a grasp of what they need to do and some idea on how they need to do it. If you don't then you should hire someone that does, or who you can feel almost absolute confidence in. Then let them do the hiring.
