The best user experience is when i never feel like the app 'gets in the way' or 'slows me down'. Everything mobile or built with javascript (damn spinners!) fails in that.
For me - multimarkdown[0], as an alternative to pandoc.
Multimarkdown syntax definition manages to be conservative with respect to original markdown and at the same time provide several needed updates, like image attributes, references within document, footnotes, complex tables, etc. All done in a style that fits original markdown quite naturally.
The program itself does everything well - reads from stdin or file, prints to stdout, very fast, reliable, doesn't have a hundred flags.
My own blogging/braindump platform, since I designed it for myself. I enjoy of working on it simultaneously with using it. I also use it for planning its own development.
I like using Word 97 for writing because of how fast it is, and how little it gets in my way. (I turned off Clippy, as much as I like him.)
Hacker News is very nice, too.
And, of course, the GNU/POSIX environment as a whole and command line in general.
The best user experience is when i never feel like the app 'gets in the way' or 'slows me down'. Everything mobile or built with javascript (damn spinners!) fails in that.