2.X
still offers a far wider variety of third-party libraries / frameworks, instructional websites and books, and experts to help you out -- I expect this will continue for a few years until 3.X
gradually overtakes it. Right now, therefore, I would still recommend 2.X
despite 3.x
's even-greater "clean-ness" and simplicity (because some cruft which 2.x has to keen around for backwards compatibility was finally wiped out in 3.x). Very few new features of 3.x are not backported in 2.x, by the way -- e..g, if you want print
to be a function, like in 3.x, in your 2.6 or 2.7 module, just put, at the start of the module, the statement
from __future__ import print_function
"Importing from the future" is a typical Python way to make new features available when explicitly requested, without breaking backwards compatibility.