In the late eighties I used to use E, an editor developed internally at IBM. My dad had
retired from there by then but got it from
ex-colleagues. I see you can get it from here now
Already mentioned is Brief, I still have the light green box on the shelf. This was ultra
customisable but like many, just used it as-is.
A super compact and snappy editor was the one built into Turbo Pascal. IIRC it used
WordStar bindings. It was so compact on CP/M that I
kept the whole integrated editor/Pascal compiler on my 8" floppies just for editing
my COBOL assignments, later on using the DOS version
in Turbo C / C++.
I also used WordStar on those OSs and I'm sure lots of you will fondly remember the
LIST viewer by Vernon Buerg. I loved that program.