One of the key pieces of software (or web based application) for Chromebook is Google Drive. It includes a word processor, a spreadsheet, and a presentation application. I find that they all work well enough for what I need to do. I like the fact that I have all my documents and programs online. It is very convenient to be able to access all I do on any device I happen to be using (of course I need to be online to do so).
There is an interesting development with Microsoft in this area. They just introduced a similar program. They now have a version of Office as a web application called office 360 personal. Unfortunately it's not free. My guess is that it is not a fully functioning version of office and so not much better than Google drive (which is free). But, if you need to use Office, there is an option. You can use Office 360.
What do you think?