I use the Emacs thermonuclear word processor for everything in my life that has to do with editing text. It’s extensibility is unmatched by any other editor out there; if there’s a feature missing that would make your life easier, then pop open the hood and add it! While it’s not the prettiest language to work with, Emacs Lisp (or elisp) is a pretty straight forward, yet deeply powerful extension language.
Why do I still use the emacs text editor after all these years? I could try explaining it to you, but I think I’ll defer this one to science fiction author Neal Stephenson: I use emacs, which might be thought of as a thermonuclear word processor. It was created by Richard Stallman; enough said. It is written in Lisp, which is the only computer language that is beautiful. It is colossal, and yet it only edits straight ASCII text files, which is to say, no fonts, no boldface, no underlining.