Use emacs
[1] Worked on in the since of configurations, my own modes, packages, etc.. I have never contributed to Emacs the project.
It's the same with Vim, if you learn how to do basic editing, the rest comes along easily, as you need it. (remember "ESC :q!", though :) )
I won't lie to you, though. Emacs is the single greatest source of yak shaving there is. It becomes your passion project as you try to craft your ultimate editing experience. It's so cool to be able to use your own passion project for work every day.