You can use the ox-pandoc library to export from Org Mode in Emacs to 65 different formats (at time of writing) including all the ones you mention.

For some formats that pandoc does not output, there are also specialised ox-format libraries.

There are even several exporters to Github-flavoured markdown. I personally find both ox-pandoc and ox-gfm very useful for that purpose.

https://github.com/kawabata/ox-pandoc