I'm finding it very difficult due to the sheer number of choices. Angular 2 supports ES5, ES6, TypeScript, and Dart. It's hard enough evaluating what our upgrade path will be from Angular 1.x, let alone which language we should end up using.

I kind of have a feeling that by the time we actually need (and have the resources) to upgrade or even start mixing in Angular 2 on our project, native browser support for ES6 will be close enough to complete that we won't need a transpilation step. That might be a nice time to do the migration.

Looking forward to hearing what other devs end up using.