Ask HN: Which front end stack would you recommend for 'platform' stability?

If you where going to pick a stable frontend setup for a project that will run for years what would you pick today?

In the next few months I'm starting a new project and I'm primarily a backend developer who does 'full stack' by the simple reason that I'm the only developer.

At present I use a heavily customised variant of Bootstrap (24 col grid, custom 'components' that kind of thing, lots ripped out) with KnockoutJS/Babel (ES2015 stuff) and Browserify, TypeScript is on my radar.

I like KnockoutJS a great deal and for the things it handles it handles them well but it's showing it's age (it's quite slow on mobile if you aren't careful) and it's user momentum has dropped off (that said I've found it to be ridiculously compatible with things and I've never actually had a serious issue with it, something I can't say about a lot of things in JS land).

VueJS seems like it's spiritual successor and has some neat features and off course Bootstrap 4 is on the horizon.

I'm aware this is a potential holy war question but as always with this stuff I'm worried I'm missing something awesome and obvious to someone in that domain, I only found out about Knockout years ago because of an off-hand comment by a front end dev I was talking to on IRC and it has saved me vast amounts of time over the years.