Virus scanners

Yes, MalwareBytes is very good. However, you only need the free version and run it occasionally when you think you might have gotten some adware or malware. Running the paid version full time just uses valuable system resources.

To reiterate there is no reason to ever install or run any 3rd party "cleaning", "optimizing", "speed-up", anti-virus, VPN or security apps on your Mac.  This user tip describes what you need to know and do in order to protect your Mac: Effective defenses against malware and other threats - Apple Community   

It's good you asked before installing any of these dangerous apps. No a Mac never, ever needs an antivirus app. Malwarebytes is perfect fully safe and is recommended. It only finds web page adds and junk. The question is whether whether a Mac can be infected by a virus? No. Read on to see why. When Apple released Catalina, we can now see (using the Disk Utility app) three icons if we click on the Container disk icon. One is titled Macintosh HD and the second one is titled Macintosh HD - Data. What does this mean? the first one, Macintosh HD, is where our Apple installed apps and files is contained. This is a read only disk. That means that no outside files can be written on it. Therefore, no viruses. It is protected from infection. The second Macintosh HD - Data is where our installed apps are located. This allows us to remove and install apps. Last, Apple has its own anti-virus app which is part of our operating system. This is an incredible way to ensure that the Mac OS is the most secure one in the industry. I hope this puts your mind at ease. Enjoy your Mac.

A good note on MalwareBytes is: The paid version has real-time protection running all the time (a kernel extension). Since there are no Mac viruses, what it mostly does is watch to see if the user has installed other types of malware. Mainly, ransomware. If it detects something other than FileVault is trying to encrypt your data, it will do its best to stop the process and shut the malware down. But you have to get well out of your way to get this kind of malware installed.

What MalwareBytes is really for is to try and help clean up malware you've already installed. And since that's on an as-needed basis, you can download and run it (which will always be the most current version) and uninstall it when you're done.

For all other - literally, all (like Norton, Bitdefender, Sophos, etc.) - AV software, do not use any of it.

I have never used any. See: https://www.apple.com/macos/security/