Bokeh is my choice. http://bokeh.pydata.org/en/latest/docs/user_guide.html

Mainly Seaborn and Plotly. Holoviews and Altair are certainly noteworthy:

http://holoviews.org/

Plotly with Cufflinks is pretty great to integrate with pandas (wide range of quick examples here: https://kyso.io/KyleOS/cufflinks-intro)

Matplotlib, due to mental inertia. But nothing I do rises to the level of "visualization," just plotting. ;-) And my plots are rarely seen by anybody but me.

Plotly works well for me - interactive plots are great, and can produce HTML to embed elsewhere.

Veusz, because I wrote it!

Seaborn