Which version of ionic can i use for developing mobile app

I am planning to develop mobile app using ionic framework, Please suggest me which version of ionic, can i use?

I have the same problem . I decide to continue to write code on v1 and not migrate my code to v2 . I see to much problems that you can read on the forum ( slow start and others ) . I move to v2 when I see a better result . I think v2 is too young .