Pretty much any distro that isn't Ubuntu. Are you asking for privacy or security? Those are very different.

For security, I'd stick to more complete distros like Fedora instead of more diy distros like NixOS or Arch. They're great to learn and tinker with, but distros like Fedora have security experts adding mitigations and security stuff in the distro by default, whereas most users of Arch or something would have to manually look up those things and keep up to date on the latest security. So basically, none of them lol.

Using more hardcore security distros like QubesOS is not very realistic as a daily driver. You'll see Linux nerds name drop it and claim they know what they're talking about, but none of them will actually dailt drive it because it's a very painful experience. Just stick with flatpaks as much as you can for pretty solid security.