Anything else can slow down your Mac, give you false positives concerning viruses, and generally wreak havoc on a machine that, when running only Mac software, does not get viruses. Most of those experts only recommend ClamXav. The folks who posted prior to your post really do know a lot about using AV software and the pros and cons.
Unless you have used these AV software products, it is not a really good idea to be recommending them. First rule of keeping your Mac safe - do not download software from any site except the Mac App Store unless it is recognized to be a safe site (like Microsoft or Adobe). Neither Sophos nor Avast are available in the Mac App Store, and Avast has been known to cause all sort of issues with Macs as we have seen here on this forum.
Malware and Viruses are not the same thing.
