Mullvad is better imo, unless you need port forwarding. I’m currently using Proton since I pay for Unlimited for that encrypted drive space, and using their VPN saves me money since I just think of the payment as just for Proton Drive. This is a change I made just a few days ago though, for about a year I’ve paid for both Proton Unlimited and Mullvad, and I legitimately prefer Mullvad over Proton, it just made sense for me to switch money wise. Can’t really go wrong between the two imo.