- Notepad
- Microsoft Word
- Twiki
- Various proprietary WSYWIG that compiles to HTML
- JIRA
- Raw HTML
- Markdown (several flavors)
With nearly every kind of migration, there are numerous pain points. The "raw" formats are a nightmare to edit and update, and the compiled ones require several hours of changing syntax, image locations, etc.
I've been getting so tired of having to re-do stuff on different platforms that more of my docs are starting as Plaintext and then written in pseudocode markup for areas that I know will change on every platform (e.g. generating a table of contents, image tags, etc).
Having just coded an entire website from scratch that was basically just documentation, Markdown comes remarkably close to doing what I want, except when the common format fails to meet my needs, which forces me to then have to switch to a specific flavor of Markdown in order to get something as basic as tables.
The docs of mine that seem most resilient to platform shifts (other than plaintext) are the ones that are written in or compiled to longstanding formats like LaTeX or HTML.
So perhaps my takeaway is, write in something readable that compiles to something widely available. That will provide the least headache.