I've heard good things about Mullvad, never used it personally, though. It's super-cool that they accept envelopes of cash as anonymous payments (or at least they did last time I checked), so you can avoid a paper trail through any payment system if you want. Out of all the VPNs out there, Mullvad seems to be the most serious about preserving privacy and anonymity.

Used NordVPN for a while -- can definitely tell you that avoiding things you've seen ads for is a good idea. Nothing egregiously terrible about them (that I know of), but they were just as expensive as anyone else, but significantly slower and less reliable. And their Linux client was command line only. (Also, the unreliability was especially annoying because, for some reason, if the VPN went down while connected -- either because of VPN server issues or because of internet connection issues -- then it would block ALL internet traffic in or out of the machine, and nothing I ever tried could change that without restarting the entire computer. Any connection hiccup whatsoever meant that I'd have absolutely no internet connection anymore until I restarted the computer. That was a pain.)

When my subscription with Nord expired, I shopped around and ended up with PIA instead. PIA has had some bad press, but I like them a lot. They're one of many no-logging VPNs, but they're (as far as I know) the only one that has a public legal record of actually snubbing a US government warrant and sending investigators back empty handed. In theory, any no-logging VPN could/should do that, but it's cool that PIA actually has done that in the past, which kind of proves they're telling the truth about having no logs and no spying on you. Also, PIA has been a bit faster and much more reliable for me than Nord ever was. No problems and no complaints with PIA -- it has all worked very smoothly and reliably, just like it was supposed to. In the (very rare) occasion when I'm having an issue with their VPN server, opening the app and changing servers always fixes the problem quickly and easily. And the cherry on top is that they have a pretty good native GUI client for Linux, so I no longer need to memorize commands for connecting or disconnecting my VPN.

The best for privacy are definitely mullvad and proton vpn. Nordvpn is the best for p2p/pirating (...not that I condone that...), but not as solid privacy wise. I know that nord and proton have excellent Linux support, idk about mullvad in that respect though.

Honestly though, if you're just doing this for privacy concerns you might as well just use something like quad9 DNS – for free. VPNs are only really useful faking you're location or pirating. Not so much for privacy or security. Quad9 + librewolf is king there.