framework: React (Vue memory leaks and available documentation it is not so great. Who wants Angular? (forces to run node v6.X with harmony flags, uses un-stable ES6-7 features, TypeScript...))
local dev: Webpack is dead (just kiddin, but it is overengineered for sure, much more control of a build than we actually need). Check this https://parceljs.org/ (recommended by substack and others)
testing: jest has good opinions but I haven't tried. So far in my current React project I'm using a combination of Enzyme + mocha + chai (for assertions) + sinon (spies, stubs...). I can help with a setup like this.
framework: Agree, being going back and forth for this, but I also think React is the way to go. More stable, more support, more ready-made components available so it looks to me it's the most future proof solution, even if it comes as heavy as it does.
local dev: Let's start with whatever React offers out of the box in its project scaffolder, instead of spending time configuring something ourselves(poorly). Webpack also has the most support in terms of plugins.
testing: Jest is the de facto for React apps, it's an all-in-one solution with spies etc. builtin. Less configuration - more time left for product dev. Enzyme is also a good addition to that stack IMO. Let's see if the default Jest assertions are adequate before adding chai.
frontend