Vim
Vim has become my go to editor; though I'm laughably "bad" at it. (e.g. I still use the arrow keys, etc) — I suppose this could be a bit of encouragement, don't worry too much about being hardcore, you can actually have a go at it "incrementally."
Spoiler: you quit with ESC and then
q!
to leave without saving or
wq
to save ☺
//uncurated://
http://www.viemu.com/a-why-vi-vim.html
List of Vim-Like tools
Reddit thread with lots of links to Vim-like tools.
Backlinks: Command Line Library I use this