Wordstar 4.0 for CP/M still holds a place of honor in my heart. Wordstar for DOS wasn't so great, and Wordstar for Windows? Ugh.
Of course, that's because, starting with Wordstar 4.0 for CP/M, Microprose ceased developing Wordstar in-house, and started buying up other companies and repackaging their software, so there was no consistent design, no logical development, no longterm vision.
It worked with Wordstar 4.0, because the firm they bought up had set out to develop an improved Wordstar, so it was the next logical evolution of that program. That wasn't the case with their future acquisitions.
I stayed with them longer than most; I actually purchased Wordstar for Windows 1.5, but it was utter trash.
Dad stayed with Wordstar 7.0 for DOS until he died in 2001; it was getting tricky finding supplies for the compatable printer, but he had no interest in learning a new program when it met his needs.