Since the rise of productivity tools like Google Docs, LibreOffice ( Windows, Mac), Google Keep (Android, iOS), and Evernote, Microsoft Office is no longer the obvious default choice. Let's help you determine what alternatives and criteria you should consider when looking for productivity software.
If we compare Google Docs to Microsoft Word, the first thing that stands out is the formatting options available in Word. Word is much better at remembering your preferred settings for font, font size, and line spacing. Word also tends to handle tables more cleanly than Docs and LibreOffice; there's less fussing around with text and column alignment. Microsoft Office tools tend to have more intuitive design for inexperienced users, and more flexibility for advanced users.
However, if your documents use basic formatting, you're probably fine with Google Docs or LibreOffice. You can get both for free and try them out for yourself, and Office 365 (the subscription version of Microsoft Office) has a 30-day free trial.
Some productivity suites are better than others at responding to changes in people's needs. For example, Google Docs integrates speech-to-text, and it's been ahead of the curve with online collaboration tools; changes you make to a document are automatically saved in the cloud, with versioning so that you can go back and undo specific edits if needed. Also, multiple users can be viewing and editing the same document simultaneously. Or instead of making an edit, you can highlight a section and add a note that appears to the right (if viewing in landscape mode), and this note can be responded to right below.
Microsoft Office has added to and enhanced its collaboration tools, but it lagged behind Docs instead of leading the charge, which is not an ideal scenario for a paid product.
However, since the introduction of Office 365, Microsoft has also gotten better about incremental updates, instead of producing one major version every few years. Google updates its office suite constantly, but it could be better at advertising new features and behaviors.
While Google Docs is free and widely accessible, there are some hurdles to using it offline. First, you need to enable offline mode; it's not turned on by default. And offline mode is only available if you're accessing Google Docs via the Google Chrome browser. Meanwhile, LibreOffice has no Internet or browser requirements, and Office 365 can go up to 30 days until it needs to check your license to make sure that your subscription is still active. (Microsoft Office 2016, the buy-once version of Office, has no Internet or browser connection either, but its license is also limited to one user.)
It doesn't have as many features as Microsoft Office, but Google's collection of online apps gets you the lion's share of what Office offers for free, including intuitive collaboration tools, easy cloud storage, and multiplatform support.
If you prefer offline productivity tools, LibreOffice should be at the top of your list. It shares a lot of DNA with OpenOffice, but it's updated a lot more frequently to fix bugs and add features. Like Google Docs, it's completely free to use.