Nobody has yet mentioned one of the main reasons to use Emacs (or Vi; substitute below as necessary): it's easily extended. Find yourself doing the same thing

Nobody has yet mentioned one of the main reasons to use Emacs (or Vi; substitute below as necessary): it's easily extended. Find yourself doing the same thing to your code over and over? Want to use a language that doesn't have syntax highlighting yet? Need to communicate with an external process? Write it up in Emacs Lisp. I don't (currently) write code for a living, and I have never spent much time using or learning an IDE. My untutored impression, however, is that even when they are extensible, it's more of an afterthought than a truly integrated part of the design. Emacs, by contrast, is mostly written in Emacs Lisp. You have access to all the same features that the people who designed Emacs used to implement its vast capabilities. You aren't limited to the set of features that the IDE designer predicted you might need.