IMO, if you can’t trust Proton then just use Mullvad.
Not saying Proton isn’t safe or anything, but Mullvad seems to be more transparent, and account creation is more private than Proton.
But depending on your use case, if you want to torrent or stream movies, I would go with Proton as they seem to have support for port forwarding and servers for streaming. If you just want to browse the internet and don’t really care about that, Mullvad is a great choice, and it should work for streaming as well.
(I should also note that I never used Proton’s premium plan, this is just from what I saw on their website, but I do use Mullvad.)