Vim. I was first introduced to this text editor back in college. It has super weird navigation rules and editing modes that would easily deter many beginners. 70-80% of my course mates gave up on it and chose something else that worked more like a normal text editor such as Sublime/Atom.

It took me several months to develop that muscle memory to increase my productivity. Today, I can log in remotely to my AWS instance, edit a few files and do it all without leaving the terminal. I hear similar benefits on the Emacs camp too.

The steep learning curve was well worth it. I don't think I've shipped any source file without opening/editing it on Vim before.

how do you feel about Vim plugins for external code editors (particularly, I'm thinking VS Code)? I somehow end up developing on new Windows machines all the time, and getting all the Unix emulation tools just so I can use Vim seems a bit over the top. Are there any enormous advantages to using Vim vs. a Vim emulator?

There are lots of vim commands and most emulators do not implement the entire set. Macros, register recording, text objects, correct repeat, recursive keymappings, bookmarks/jump history, and ex mode are the most frequent casualties. Because everybody has a different subset of vim commands they use an emulator that works fine for one person will be unacceptable for others. I personally can't stand any of the VS Code vim plugins, which is a shame because I really would prefer to migrate from vim to vscode for the rest of the vscode ecosystem. The best emulator I've used is Evil (the emacs one, install spacemacs if you want to give it a go) and I find the InteilliJ and Atom emulators to be okay.

There's also plugins that are almost never carried over to emulators (though surround is in Evil):

EasyMotion [0] - Lets you jump around in complicated ways. I use the following config to be able to jump around in a minimal number of keystrokes:

    let g:EasyMotion_keys = 'jfkdlghtyuievnbsa'
    let g:EasyMotion_smartcase = 1

    nmap  (easymotion-bd-W)
    nmap  (easymotion-s)

    nmap s      ysi
    nmap S      ysa
    nmap s$     ys$
    nmap sv     gvs