Nowadays (old and retired), I type a lot of Markdown into Noteplan’s excellent Markdown editor, but BBEdit is also always open on my Mac for miscellaneous text and Markdown tasks.
For example BBEdit has the chops to roll up a year’s worth of voluminous Daily Notes in Markdown format without bogging down. And BBEdit’s Text Colors setting allows me to mimic the Markdown theme that I use in NotePlan. And, of course, BBEdit can open just about ANY type of file for me to poke around in and satisfy my curiosity.
I’ve tried too many text editors to count, but BBEdit is the one I settled on at home on my Macs.
My working career, however, was spent on Windows and UNIX. I used the excellent Windows editor called EditPlus (with John Gruber’s Perl script installed to support Markdown syntax!) On UNIX, I used the classic vi editor (always present on any UNIX-like system I had to log into!) Also lots of anonymous editors built into Java IDEs like NetBeans, IntelliJ, and Eclipse.