The biggest issue is that there's no real compelling reason to migrate away from Python 2 now. It's not meant to be an attack on Python 3 - Python 2.7 is still

The biggest issue is that there's no real compelling reason to migrate away from Python 2 now. It's not meant to be an attack on Python 3 - Python 2.7 is still well-supported, and is plenty good enough for a lot of us. That said, if I were starting out now, I'd start with Python 3.