This is very debatable nowadays so I'll tread carefully. I'm running Windows 10 with its own Defender as antivirus. Coupled with that is Malwarebytes Premium which has to be paid for annually. That's it, no other security software. This set-up is on three laptops. Haven't run a free antivirus third party software for a few years now as I have no need for them. Others might disagree but it works well for me and my browsing habits... that can be sometimes a bit risky when looking for free Apps.
iPhone X review