For Windows: The built-in Defender finds viruses as well/badly as any of the paid ones. Known viruses, that is.
Malwarebytes paid version might well add another defensive layer to that.
McAfee and Norton use ridiculously exaggerating terminology: For them everything is a "threat" or "problem" or "something that needs to be repaired". Honestly, how big of an issue 1 Mb of temp files really is? Or outdated virus signatures in a computer that hasn't even been on for a week? And is the program broken if it needs to be repaired? Even if the issue is that you haven't checked for updates manually when auto-update is pending?
Exactly what I do.And I agree with those two apps, they are bloated resource sucking nonsense, that don't work any better than free stuff. IMO. I've yet to get any thing in years. Usually false positives.
Decades ago, I took on the habit of partitioning my drives so that ONLY windows was on drive C. I changed all windows and browser temp folders to it's own drive, all software on another, and all my person files on yet other drives. (All the same size drives for HHD.) Saved the registry file for all these changes. This way, if anything happened to Windows I simply formatted drive C:, re-installed Windows, hit the reg file and I was up and running fresh with everything intact in 1 hr.