PyCharm is by far my preferred python IDE. It offers helpful syntax highlighting and debugging features that are mostly unmatched by programming applications such as Sublime Text and Atom. The only gripe I've had with PyCharm is the limited (rather ugly) themes it offers. Luckily, PyCharm is highly customizable and it is possible to change virtually every single aspect of the UI experience. There are hundreds of free PyCharm themes that you can find, so you can save the pain of making one yourself. After having tried around a hundred themes, I found an Atom-based one which I found quite nice. I still found some of the colors to be somewhat off, and I modified this theme to make it truly feel like Atom.
In order to try this theme, all you have to do is to download the .jar settings file, go to File -> Import Settings and select the jar file. You can select which aspects to import, such as the Code Style, Editor Colors, Notifications, etc..
Feel free to modify this theme to suit all of your preferences. I hope you enjoy it!