From a security/privacy perspective, which of these OS’s would you consider to be the most secure

Kali and Parrot are for attack, not more secure.

For security/privacy, remove anti-libre software. They ban us from removing malicious source code. Use Parabola or other libre software here.

An operating system controls its apps, so controls guests in these apps, so a guest is never safe when its host is anti-libre software (macOS).

Because they ban us from changing the source code: that’s what they won’t tell you.