Others
These are not the only IDEs available for Python development, nor are they necessarily the best. Other popular options, based on various professional and semi-professional group polling, include:
PyCharm (Community or Professional version): PyCharm shows up pretty consistently as a popular IDE for Python development. Its feature list includes most of the same bells and whistles that have been noted for Geany and Eclipse/PyDev tools, and it also features out-of-the box integration with Git, Subversion, and Mercurial version control systems, as well as UI and tools for working with various popular RDBMS, such as MySQL and SQL Server in the Professional version. It's probably a good first choice for the development of web applications in Python, provided that its project management functionality isn't going to be overwhelmed by the code base. PyCharm can be downloaded at www.jetbrains.com/pycharm.
Visual Studio Code: VS Code is touted as being a lightning fast code editor, and has a lot of functionality available through a large collection of extensions for various languages and purposes. Although it's one of the newer IDEs in the wild with Python support, it's fast becoming a popular choice for scripting tasks, and has a lot of potential for larger, application-centric efforts as well. Visual Studio can be downloaded at code.visualstudio.com.
Ninja IDE: Judging by its feature list, Ninja has most of the same base features available through Geany, with the addition of a single, built-in project management subsystem that sounds useful and attractive. Ninja IDE can be downloaded at ninja-ide.org