I like to write my rich-text files in plain human readable formats to which I am accustomed with and where I don’t have to type all the markup myself. My app HTML Editor helps me and others to do that in Android. But in desktop platforms it is easier to use shortcuts to write markup.
For example Word, Libreoffice etc use CTRL-B, CTRL-I for bold and italic text. But they are too heavy and insert unnecessary html in their code. Recently I came across an interesting tool called markItUp. It is very customizable and supports custom keyboard shortcuts.