In my opinion they aim for different groups of developers. It's more of a question if you like monolithic frameworks like django where you "get more" at the expense of flexibility vs. pyramid where you are in control of what is going on, the components are better - like default orm sqlalchemy or templating but the learning curve is a bit stepper - but you are way less likely to reach a dead end when "something happens" in the middle of the project(yeah i know it shouldnt be the case but we all know how reality is sometimes).

Personally after I did django tutorial and more "magic" appeared, I decided it's not a project for me.

Django is like your first date, attractive on first sight, but gives you more and more headaches till it outweighs the pleasure it brings you, so you break up with it and marry Pyramid, who after delivering three baby projects for you, is still in pretty good shape. And there's always the sexy side of her if you dig deep enough.

How about the others? web2py is too old, Werkzeug has a funny accent, and Flask is not 18 yet.