Aurelia hands down. For years we've used Knockout, Angular, and Meteor, all of which have goods and bads. But Aurelia amazed us. It is the best thought-out framework I've used. SO much easier to pick up than Angular 2 and React, and it's so "out of the way" I forget it's even there sometimes. Not only that but our code-footprint is much smaller, because we are writing less code. When you hear grown-up developers giggling in their offices when using it for the first time, you know it has to be good.

Used it for a long time, but got tired of it crashing and losing my work every time I closed the lid on my Mac. It was a known issue for a long time, so I switched over to MongoChef and will never go back.