Proton unlimited is pretty enticing with the email and drive, especially since I'm using Zoho for free custom domain email, I wouldn't mind using proton.
Surfshark offered a similar deal that I bought a few years back. At the time it worked just fine for me, but they don't offer port forwarding (at least they did not at the time I was using them), and they don't have a Linux GUI.
I thought about proton, for about $12/month you get premium access to all proton services, like mail and drive. not a bad deal if you like the ecosystem, but no linux GUI is a pretty big -1 for me.
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Also, it doesn't seem to be much more expensive than something like ExpressVPN, though that is pretty expensive at about $13 USD monthly. Way cheaper to buy yearly though. In comparison, Mullvad is a flat 5 Euro (about $5.20 - $5.40) per month. Other VPNs seem to be about $10-$13 per month.
I have not tried them, but always stayed away from them due to aggressive marketing that really put me off. there was a good year or two where I was bombarded with NordVPN ads and sponsors, and still get the occasional advert about them. It may be worth trying though, I have colleagues that use it.
ivpn looks nice, it looks like they are taking a similar approach/structure to account creation like mullvad does. I don't like the 7 device limit though, but it is still 2 more than mullvad.
+1 for GUI on linux.
Just looked it up and found this post (link here) by PIA from a few months ago, looks like unlimited devices is a recent addition to their service.
It looks like IVPN is pretty similar in terms of anonymity