Built by the company JetBrains who are pretty well known for their IntelliJ IDEA product that works with Java and the JVM in all its forms.
Pro Automatically figures out what test to run based on the method the cursor rests at a given time
PyCharm, based on what method or class the cursor rests, can figure out what tests to run and perform them with a keyboard shortcut or two, without breaking up the flow and need to switch to a command line interface.
Pro Excellent integration with debugging tools
All the debugging can be done inside the IDE. Breakpoints in the code can be added using keyboard shortcuts or the mouse. When the code is executed through the debugger a toolbar pops up with all the relevant context needed for the debugging process.
The whole process is smooth and painless and you don't even have to switch windows to do the debugging.
Pro One of the best autocompletion engines around
PyCharm has two types of autocompletion: structural completion and word expansion.
Both types of autocompletion work extremely well, have little to no problems and are quite fast even when loading suggestions on the go.
Pro Great for navigating large codebases
PyCharm has amazing code navigation implementations. It supports both goto symbol and goto declaration. The former finds classes, variables, functions, etc by name. While the latter is used by moving the cursor on top of a symbol and by using the mouse or a keyboard combination it finds the declaration of that symbol and takes you there.
Both of these features are extremely helpful when consulting large code-bases and when trying to understand an API written by someone else.
Pro Great pip support
PyCharm offers great pip integration. When opening a project it automatically checks for a
requirements.txt file in the root of the project. If it's found, it checks if all the libraries are available in the interpreter. If one or more libraries are missing, it issues a warning and asks whether you want to install any missing libraries.