What is the Most Underrated Free Security Application?

[Ink]

Windows itself is the most underrated security software (it is considered like "free" because you already have it).
1 smartscreen
2 user account control (set to high)
3 standard user account for regular use
4 two-way firewall
4 default Windows 10 apps that run in appcontainer
5 Windows Defender, which understands how Windows works, and runs at kernel level

No one likes built-in security tools, that's why people complain when they get infected with malware and blame it on the Windows OS or AntiVirus.

UAC on default is sufficient also, not necessarily needed to be run on Highest settings.