In today’s world, if you have clear concepts of not opening attachments from unknown senders or even from known senders that look fishy, you don’t need an antivirus for Windows, just use the one that comes with the system itself. For Mac, you don’t have to worry about viruses anyway.
But we do recommend antimalware software running on your desktop computers. Forget about mobile devices (for these, make sure that you turn them off every two or three days. Restarting will not do the trick, Power them off completely and start them up after a few seconds – This will remove the temporary files in which most of the malwares out there rely on), our top recommendations: Malwarebytes and Emsisoft, Glenn uses Malwarebytes, I have a subscription with Emsisoft.
Emsisoft only runs on Windows. Malwarebytes is for both Mac and Windows.