By using AngularJS and Dart (AngularDart) you will get to use best of both the worlds. I would recommend reading this answer.
The tld;r is that AngularDart team learned from the mistakes done in Angular project and they have already already addressed these issues in AngularDart. So, if you are planning to use Dart go with AngularDart. This way you will use a better Angular + Dart.