Emacs

I tried Emacs six times before liking it. The time it stuck was when I was editing some code in a language where the include/import statements almost matched the directory structure in the filesystem, but didn't. So, in Vim, I could cursor over an include statement, type gf... and not quite be able to instantly open up the included file. The way gf worked was that it was written in C as part of Vim, and to tell it where to look was a matter of configuration. But I needed a bit of code instead, to make up a couple of places in the filesystem to look on the fly, when I wanted to find-file-at-point (the Emacs term for Vim's gf functionality). Not only was find-file-at-point written in Elisp, but it already had a place where you could hook some custom code in, and documentation about how to do it. The documentation was available inside the editor (as you might expect from using Vim's :help), but it also had a link straight to the Elisp source. I was able to try out my function, change, and try again without restarting Emacs, and debug it step-by-step using edebug.

Anyway - have fun with Neovim. I hear it's spiffy. :)