I do use Mullvad for most web browsing though. But Imgur for example is blocked on it, and it's blocked in the UK, so I need NordVPN if I want to see any images there.
Most people's VPN usage is literally just geolocation restrictions and Nord is really good at that.
System wide proxy configuration doesn’t actually always work system wide.
A VPN tends to have more success in encapsulating all application traffic (or all desired application traffic, if you’re so inclined to configure your system)
AFAIK, at the moment your choices are AirVPN and ProtonVPN. AirVPN has static port forwarding and Proton has UPNP port forwarding.
I miss mullvad dearly, and I might try proton after my 3y sub is up.
It makes more sense when you know they're privacy activists first, businessmen second. But Mullvad shows you can be pro privacy and still offer great UX and a sleek site and client.
Btw, if you're managing things in CLI, you could take a look at their Hummingbird Suite. AFAIK it has a killswitch.
What sucks with Proton is that you can't share the VPN account with friends, because it is tied to your Proton account. They should create a vpn.proton.me subdomain that you can create a special managed account on that can only touch the VPN settings.
Hummingbird doesn't support wireguard iirc, which is a deal breaker
With DCO, OpenVPN can perform almost as well as Wireguard, sometimes even better. Although with more performance overhead so not the best choice for laptops and phones.
Tangentially related but I kind of wish Wireguard looked more toward the future and had included AES as alternative to ChaCha20. At the time of development, many ARM devices didn't yet have AES acceleration which is why ChaCha20 was needed for wide hardware support, but they do since ARMv8 which became widespread in 2015. Intel and AMD have had AES acceleration for a long time. And then ChaCha20 would have been the fallback on MIPS and RISC-V.