I use Django. For the most part it does the heavy lifting and then gets out of my way and lets me code. Another large factor I really like is the peace of mind knowing that it actually works in production environments and isn't impossible to scale. Also, their documentation rocks.<p>The only other one I've really checked out is web.py. It has a much more raw feel to it. I'd probably switch to it if for some reason Django started getting in my way a lot.