1. Cross-platform ( Windows, Mac OS X, and Linux ).
2. Firefox style extensions.
3. A lot contemporary color schemes.
4. Built-in FTP and SFTP, even with key authentification. It allows editing remote files directly and working with cloud-based projects.
5. Not Java-based. Java-based applications are very memory consuming.
6. Polyglot (as for languages ).
7. Many unique features.
8. Syntax support for rare, not popular and commercial programming languages.
9. Auto-completion functionality is excellent.
10. Syntax checking is configurable / customizable / extensible for every specific programming language. There are internal and external linters / hinters / etc.
11. Free full-fledged IDE.
12. Support is very responsive and one can easily contribute or post an issue.
13. Intuitive interface.
14. Easily integrates into desktop environment (GUI theme, system environment variables, custom installation folder, etc.).
15. As for my experience Komodo Edit never crashes.
16. Native unicode support and unicode compatibility checking.
17. Feature rich and various unique features.