Heh, I have half a novel written (relatively recently) in Wordperfect 6.0 for DOS. I need to get on finishing it... I tried Wordstar after hearing how many current professional authors still use it, but the only version I could find online was so ancient it doesn't support subdirectories (3.0?) I didn't think it was worth my time to learn.
For general text editing I still use
QEdit 2.something for DOS *a lot* - to the point of firing up DosBox on a modern machine to edit things with it. Putting a copy of QEdit in the path is one of the first things I do when setting up a new system. It has some interesting features like key macros and the ability to open wildcards - i.e. 'q *.nfo' from the command like will let you rapidly flip through all .nfo files in the directory. Extremely useful. Why can't modern editors be this convenient?
(Interestingly if you download QEdit 2.x from somewhere and F11/F12 pan the screen window up and down without moving the cursor line, you're using *my* QEdit - those are macros I added years ago. I think I uploaded it somewhere in the '90s for some reason, but it's still kicking around the web; I've found it in a few places since then.)
On Linux/OSX I have a drop-down console that appears with one keypress (F12 on Linux, ctrl+~ on OSX) and I edit whatever with VIM. I only learned it in 2008 but it became intuitive really quickly. That said I still don't have *all* the features down. I have VIM for DOS too but I don't use it as much - QEdit loads quicker. Another interesting VI-derivative installs with OpenWatcom C; it's more of a screen editor like QEdit but it implements VI's command mode too. Best of both worlds.
Here's a good rundown on DOS text editors from a programming perspective (with some downloads as well.)
If I *really really need* to use a 'modern' word processor I stick with LibreOffice (I can't stand MS-office-anything but seeing as I don't run Windows on anything it's a non-issue.) That said the fifth time I have to go back and 'correct' an auto-capitalized word that I didn't want capitalized or undo some stupid auto-formatting in Libre I usually rage-quit and go back to a text editor.
(This post was written in VIM. Copy+paste FTW.)
*** Edit: How could I forget
Speedscript 3.2 for the C-64? I think my dad typed in all 6kb of assembly code from Compute Magazine to get this one going. I seem to remember doing elementary school assignments in it, was probably the only kid in the class submitting typed papers @ 10 y.o.! My handwriting has always been terrible so I'm sure the teachers appreciated it. ***