Favourite text based word processing software

Hello group I'm toying with the idea of writing a simple word processing package along the lines of Wordstar for my Retrochallenge 2015/01 entry. I have used many word processing packages over the years on many machines from 8-bit machines to mainframes. Within the following bounds I'd love to know the packages that have been the favourite of list members over the years and why. If I implement this I'd be looking to keep within the following bounds: * text only - ideally support VT terminal 80x24 or 132x24/36/48 or DOS 80x25 display size. * two printer drivers - text only and Epson LQ (or possibly IBM Proprinter) * support small range of printer specific fonts * support proportional text So a little more than a text-editor but only enough to support simple formatting and styles (bold, italic, underline for example). Ideally I'd like to implement a clean, logical design without many 'bells and whistles' concentrating on the core functionality. Kind regards, Mark.