[Update: February 2019 – A few months ago Microsoft released Office 2019 for both Windows and Mac so you should buy Office 2019 now, instead of Office 2016.]
If you use Office 2011, it’s time for you to start planning your upgrade to Office 2016. Office for the Mac includes Word, Excel, PowerPoint and Outlook, if you buy the Business version. There are a few reasons for you to start planning to switch to Office 2016. Initially, as of October 10, 2017, Microsoft will not release any more updates for Office 2011. This means they won’t fix any more bugs, release security updates or provide email or phone support. Additionally, Microsoft indicated that they have not tested Word, Excel, PowerPoint or Outlook with macOS High Sierra (aka OS X 10.13) which Apple released in September 2017. Thus, if you choose to use Office 2011 in High Sierra, you might encounter issues. Lastly, Apple has indicated that High Sierra is the last version of the Mac operating system that will fully support 32-bit apps.
[Update October 2019 – While Office 2011 was no longer supported by Microsoft it continues to function reasonably well with macOS Mojave (aka macOS 10.14). Office 2011 does not function at all with macOS Catalina (aka macOS 10.15)]
So the writing is on the wall. Make your plans. When the time comes, you could either buy a copy of Office 2016 or you could subscribe to Office365. Office Home & Student 2016 costs $150. This includes Word, Excel and PowerPoint. Office Home & Business 2016 costs $230 and adds Outlook. If you want to subscribe to Office365 you can choice from either Office365 Home or Office365 Business plans.