I used to see many developper that keep using Angular 1.4 for new project whereas Angular 1.6 was released.
So the question is, is there any problem in those version that make developper want to keep using 1.4 ?
Upgrading a large system can be a costly procedure. There can be many types of issues involved most notably those related to compatibility and dependencies. This could be a reason for not upgrading existing applications. However, for building creating a new projects, it is advisable to go with latest stable versions to take the benefits of new features and enhancements.