Emacs is arguably the most powerful tool available to the modern programmer. Vim’s pretty close. Both require more effort to learn than say Atom or Sublime Text. But, the additional start-up effort pays off quickly.
Like Scheme, they both suck out-of-the-box. Unaltered they’re both horrible bare-bones skeletons of an editor. Their potential is incredible though. If you’re just going to do something quickly, and never spend the time to customize them, they are a terrible choice.
But, if you’re willing to invest a little time and tweak them to your needs (a macro here, a plugin-there) then you’ll end up with an amazing tool perfectly suited to your brain and your approach to programming.
Watching an experienced Atom / Sublime user with vs. an experienced Emacs / Vim user with a setup customized to their brain is the difference between watching 8 year olds attempting to play Soccer and watching the final match of the World Cup.
Scheme is my Vim. I’m still learning how to customize it, but I can see the possibilities.