I considered both when I first got started. Django was just too hard for me. When I read code using a framework I've never seen before, usually I can still kind of tell what it does. It might be my own stupidity, but when I read Django code I have no clue what it does.

I did consider Flask, which is much more similar to web.py, but eventually chose web.py because I was a fan of Aaron Swartz' work at the time.