Can I plug my Veusz GUI plotting application? It's written in Python, so it's also a Python plotting library. It's more a object-orientated library than matplotlib, so plots are built out of widgets.

https://veusz.github.io/

Altair is getting pretty good. It's a bit like ggplot in that it's declarative, though I wouldn't suggest dropping R for this any time soon.

https://altair-viz.github.io/

Another option is to use plotnine, which is intended to be a ggplot2 clone. It uses matplotlib under the hood, so if something isn't right you can tweak it. That was the main drawback I found with Altair: your declarative code is almost literally dumped to a json file and then rendered by a process external to Python, so good luck tweaking your plot.

https://github.com/has2k1/plotnine

I think there are some pretty good arguments for why Altair (which is just Python bindings for Vega Lite) should be people's first choice. I've written about this here https://medium.com/@robin.linacre/why-im-backing-vega-lite-a....

In my mind, ggplot2 is actually more comparable to matplotlib in that it's more expressive, but less intuitive. It's interesting that the 'successor' to ggplot2,ggvis (which is on ice) , used Vega as a backend.

Plotnine is a verbatim port of ggplot2. There are other ports but plotnine is the good one.

https://plotnine.readthedocs.io/

bokeh (https://github.com/bokeh/bokeh) and seaborn (http://seaborn.pydata.org) are popular

Since version 4, plotly isn't horrible. It's okay. It does basic things fine enough that I use it almost exclusively. However, I most plot for personal analysis, not for presenting to others.