Years ago Sun started an office suite that later became Open Office, when
they sold it to Oracle the new owners wanted to take it off in a direction that made it a lot more dependent upon various Oracle products. The open source community that had been working on Open Office for many years did not like this. When discussion about this with Oracle broke down the majority of the people involved walked away from Oracle and Open Office and started a fork of Open Office and they called in Libre Office, Libre as in free. This has now progress well past Open Office as the better people are working on it. They've also reduced the dependency on Java that Sun had been introducing into Open Office.
Today, Libre Office is far superior to Open Office and also much better than Microsoft Office. The only problem you may have is if you have a LOT of VBA macros, I've not tried Libre Office with VBA macros, so I don't know how it will go.