Sacrificing the awesome 3.x features (f-strings, typing, metaclasses, object model improvements) to hold onto a deprecated and soon-to-be obsolete version of Python seems bad to me.
There are a number of improvements, including how you define them and the things you can do with them. Some of these tie in with other language features, e.g typing.NamedTuple[1].
There is also PEP 487[2], which means you can do more without needing a metaclass.
Are Python 3 metaclasses a significant change?
[0] https://www.python.org/doc/essays/metaclasses/