When I first owned a Windows computer back in the 90s, I used Zone Alarm as a picky firewall and Norton by Symantec for the antivirus software.
Through out the years, I used AVG Antivirus, Avast, Windows Defender, and McAfee as antivirus software until Windows 10 rolled out. And after the era of Zone Alarm, I stuck with Windows firewall.
Windows 10 always updates antivirus definitions even if another software is set as the default. I was watching the Windows updates and discovered that. When I bought a Dell laptop, I could not remove McAfee from the cart. When I discovered this background activity, I permanently removed McAfee. I set up Windows Firewall, Windows Antivirus, Windows Ransomware protection, and additional security features.
But isn’t McAfee worth paying for each year, you might ask. I don’t think so. I think that you are paying for a name brand that supports Dell. And I have serviced computers with McAfee and Norton by Symantec that had 400+ hidden Trojan viruses on them. Those paid software choices were not doing their intended jobs.
Now on macOS, the only software that I would recommend installing is the free version of Sophos. But now I don’t use it or any other antivirus software and I recommend that you don’t install them either because it can ruin the installation. Especially those cleaning tools, except for CleanMyMac, which has proven to be safe.
macOS has a built-in Firewall under System Preferences » Security & Privacy that is off by default but I recommend to turn it on. There’s also an antivirus software hidden deep in the system that is always running and you cannot modify. Apple updates it often through system security updates.
I would recommend that you use Safari (macOS only), Firefox (set as Strict in Preferences » Privacy & Security), Google Chrome, or Microsoft Edge (which strips the Google data mining but leaves the Chrome Store enabled, last I read). On older macOS systems Google Chrome is RAM hungry. Safari or Firefox are best choices for macOS. If I weren’t a web developer, I’d use Safari. If you are using Android and are a macOS user, I recommend Firefox as your main web browser so you can keep your bookmarks in sync and send tabs back to your different devices.
And while I’m on the topic of security, use 1Password or LastPass to manage your passwords in a paid, encrypted service.