If you're going the JS route, the benefits of Angular2 over React are marginal other than you get everything working out of the box after you've done all the boilerplate, it feels somewhat simpler as well and less things to think about since you are given all the tools you need to get started.
I've found that with Angular2 Dart, a lot of the setup you need to do on the JS side is taken care of - JS minification, error checking, boilerplate is a lot less, sass + less compiler with a single line in your pubspec.yaml file.
I've done a writeup recently on my Angular2 Experience: