At this point, any of them.

Strictly speaking, fully loaded Kali Linux (or an equivalent build) so you can learn to do subversive things against adversarial networks.

But really, if you just want an operating system under your control, every version of Linux will do that for you.

But Hannah Montana Linux will do it for you with the most style.

Admittedly I'm not keeping up on this, so maybe outdated but it used to be Tails.

Depends on your opsec scope and use case. It also depends on the software you are running ontop like your browser or other services that probably have even more data on you.

On that note, what Linux distro are best for privacy?

Funnily enough, GrapheneOS Android.

All popular general purpose Linux Desktop distros suck in terms of privacy and security out of the box. It is possible to configure stuff like SELinux but that is very far above what even a competent Linux user is able to do properly.

Tails and QubesOS are amazing in terms of security and privacy, but their lack of general usability means very few people are going to use them day to day. For most users, they are impractical.

GrapheneOS has a mix of security, privacy and usability that makes it attractive choice for anyone somewhat competent with technology and caring for privacy.