I’m sorry, I didn’t realise it wasn’t in FAQ but in the alpha announce what I was thinking about:
Let’s address the elephant in the room: “What about Ionic 1? What’s going to happen to it?” First of all, we will absolutely continue supporting Ionic 1 for a long time. In fact, there are a number of improvements we’re working on, including upgrading to the next version of Angular. At the same time, we are going to work to make it easy to upgrade to Ionic 2 slowly over time, as the community also starts to adopt Angular 2. While we aren’t going to apologize for wanting to push Ionic hard into the future, we also understand that software can live for a long time, and should be supported for as long as possible.
1.3 is stable, 2 will be developed longer and more of course, but it’s in beta, I’d say go for ionic2 beta it’s pretty stable. But if you prefer 1, it’s not going to break or anything if it’s not updated to the latest latest latest angular 1 :-).