Ember barely gets mentioned and includes each "piece of modern web applications" OUT OF THE BOX with a great support community. I love not making all of those decisions and doing all the integration BS work. Ember feels like the worst kept secret.
Ember CLI is also awesome, and Ember CLI Deploy is damn cool once you get it: http://ember-cli.com/ember-cli-deploy/docs/v0.4.x/lightning-...
Deployments take tens of seconds. Roll-backs take single-digit seconds. Previewing not-active-but-uploaded versions of the UI is trivial. Everyone does the same exact thing when they deploy (or throw it on Jenkins for even more fun).
Ember is a pretty cozy ecosystem in comparison. You get Babel, JSHint, npm and QUnit - out of the box. Most of which can be swapped out for your preferred libraries.
Ember gives me confidence, that I can keep maintaining the app with very low effort, especially now, that the Ember community is releasing a LTS version.