I think it makes sense to learn v1 right now, mainly because with 1.3 and 1.4, the delta between Angular 1 and 2 is shrinking.

Some quick tips for making the transition smoother:

  * Use "controller as" syntax: http://toddmotto.com/digging-into-angulars-controller-as-syntax/
  * Use ES6 if you want http://blog.thoughtram.io/angularjs/es6/2015/01/23/exploring-angular-1.3-using-es6.html
  * Build components using element tags not classes. (attributes are fine but components are better expressed as unique elements).

Note: a lot of of the Ionic components (as mark up) won't be changing.

Here's a talk (including Andrew Joslin, an Ionic dev) about moving from 1.3 to 2: https://www.youtube.com/watch?v=pai1ZdFI2dg