For one reasono another im not seeing any of the currently OSS solutions like LibreOffice/OpenOffice.orgwould not gain much traction and will remain niche even as the MS/Goog options remain entrenched.

The path taken by Blender(propreiety initially to open source) to reach industry lead would to me seem the most viable to make a dent.

In that i think best cost effective options like WPSOffice or Corel Suite , would be a good option.They have the professional usability in the interface and functionality.

Corel is basically leaving the market wide , by mostly collecting rent from lawfirms as they are well taken care of there.Considering they used to have viable Linux options , seems a lack of vision theer to pick up marketshare.

If UI is your concern, check out Collabora and OnlyOffice, both have a modern ribbon-like interface and looks similar to MO.