You may get varying opinions on this. Trend Micro makes an excellent AV program for Windows, but IMHO it just isn't necessary for Mac unless your usage habits are very extreme (e.g., you are disabling its security features, installing programs from unknown developers, opening super sketchy attachments, have people using the system who are completely unable to spot potential scams/PUPs, etc.) A huge portion of those saying they do need AV are...well...those somehow involved in the development of programs pertaining to fighting malware. It's just not very easy for malware to access your files or system files on a Mac. Macs do get hit with malware, but this malware is generally more an annoyance than it is a serious security threat, and it can be mostly avoided by safe usage habits and using an up to date web browser. Macs are by no means immune, but its security features are quite robust. At least as of right now, you generally don't hear many end user accounts of major damage caused by malware on Macs. So, IMHO, the free version of Malwarebytes is perfect for most users.