Cheers! Answering you for all three (at the moment) comments asking:
Okay, here goes.
In brief, Python 3 adds work without adding significant (to me) value.
As others have pointed out, you don't get anything from converting an existing project from 2 to 3 other than compatibility with 3. If the Python 3 proponents were to succeed in killing 2 then that becomes compelling, however, since I intend to maintain 2, I don't care about compatibility with 3.
As I have become older my tastes have changed, and nursing an old friend seems easier and more fun than trying to stay up to speed with the new hottness. Especially since it just isn't that hot.
Some details:
First, I see 2 and 3 as different languages. The degree of similarity is not relevant (to my evaluation of which to use) since they are incompatible (in other words, incompatibility is binary not scalar.) Since the abdication of the BDFL it seems to me to be even more appropriate to treat them as separate. I don't know how or why but Guido was good at language design. I feel like he lost his touch somehow, and then he left anyway, so the magical "thing" that made Python so sweet in the first place is gone. (I won't comment on any particular PEPs. It's all been said by others elsewhere.)
I feel that Python 2 hits a sweet spot in language design as compared, not just to other Python versions, but to other languages as well. (If you can't use Lisp or Smalltalk or Prolog at least you have Python.) Python 2.7 is a local optimum with a clear view and steep sides, eh? Python 3 goes crashing down the hill and into the woods...
From this POV the cessation of modification to Python 2 is a boon. It's stable and can only get asymptotically more so over time. It also means that projects like Snakefood that do meta-programming can stabilize because the underlying language is stable. We are only now getting type checking and such, and e.g. MyPy has to expend resources to deal with changes to Python 3 or risk bit-rot.
Python 3 continues to include dubious design decisions that then must be dealt with by other projects/tools. I.e. syntax highlighters have to be modified to deal with "fstrings", etc. It drives a continuous process of change for the sake of change without introducing anything fundamentally new and useful. As a developer, your knowledge is depreciating as you sit there because the language is in flux. With Python 2 the thing you're studying and using is stable. In fact, it's possible that the total amount of code could contract in a stable regime. Especially if you have dev time to work on it (that isn't wasted on pointless new features that then engender additional work to learn and use.)
You can also spare cycles to work on things like improving the standard library documentation, or the packaging/versioning mess, or really anything other than tweaking the language (and, again, making more work for everyone without adding fundamental new facilities.)