I really, really wanted to say to you Python 3, because:
- It is better (it fixes some annoyances)
- Django is working really great with it
But some things (that Django uses, but are not Django) are not working yet. Things like MySQL adaptors, South, etc
Or maybe go with Python 3 and wait for the issues to be fixed, they probably will, soon enough
There are ways to write software that's compatible with both Python 2 and 3 (using six for example: http://pythonhosted.org/six/)
But I guess it's mostly developers not having the time to update (it's easier if you kept it updated and not using some old constructs)
ETA: That said, the advice to stick to Py2 right now is probably good. There's still some key missing 3rd party packages, so you'll generally be happier as a Py2 user right now.
I'm really looking forward to migrating a few projects up to Python 3 and Django 1.5. It's going to be awesome!
but... a lot of packages are not ready for 3 yet. So it depends how far you want to go.. Playing around by yourself? I'd go with Python 3... if you need to leverage a lot of the packages you'll need to drop down to 2.7
Plus, 2 is not going away in near future, and you'll be able to pick up 3 easily after that