WPS office, formerly Kingsoft Office, purportedly looks more modern than libreoffice or openoffice. Runs on Linux, Android, iOS and Windows.

LibreOffice is evolving rapidly, runs on Linux, Windows, perhaps more. Forked from OpenOffice.

OpenOffice, owned by Oracle, acquired when Oracle bought Sun. Some sites prefer OpenOffice's license to that of libreoffice. Runs on Linux, Windows, perhaps more.