There are three excellent office suites that are all popular with ABers.
They include WPS Office (formerly Kingsoft Office)
http://www.kingsoftstore.com/
and LibreOffice:
https://www.libreoffice.org/
However by far the most commonly used (meaning that you'd have no difficulty finding help from other ABers if you ever needed it) is the wonderful OpenOffice:
https://www.openoffice.org/
It's what I use and I can thoroughly recommend it.
Just a small hint though:
Third-party office suites (such as OpenOffice) save files in their own formats (rather than Microsoft ones) by default. That means that you can't send them to people who've only got Microsoft Word on their computers because they won't be able to view them. You can get around that problem simply by using 'Save As', rather than 'Save', and selecting a Microsoft format. However it makes more sense to change the default setting, so that OpenOffice automatically uses Microsoft formats anyway. There are simple instructions here:
http://helpdeskgeek.com/office-tips/set-openof%EF%AC%81ce-org-to-save-in-microsoft-of%EF%AC%81ce-format-by-default/