CherryPy has had Python 3 support for quite a while now. Not many Python frameworks have that. Pylons just got it, so I'd go with CherryPy. You can get WebSocket support too, and documentation is OK.
I see so much stuff about flask and bottle, but not much about cherrypy, what do those do for you that cherrypy doesn't? cherry py has always worked well for me, I'm a fan.
