LibreOffice Online is a viable alternative in my opinion. It integrates with NextCloud and allows you to easily share and collaborate. You can even get a "share link" for your documents like in Google Docs. There are some caveats though. Latency is unacceptable. Google Docs renders documents client side allowing characters that you type to immediately echo to the screen. LibreOffice renders documents server side with a noticeable lag. LibreOffice has the benefit of better interoperability with MS Word than Google Docs has.

I would also recommend trying OnlyOffice as some have recommended.