When I was looking, I boiled it down to Mulvad or Proton. I went with Proton because they were offering a sale at the time. FirefoxVPN is just a rebranded Mulvad. I've since heard that iVPN is fairly private, or as private as you can get in this day and age, but I know little about it.

Express is owned by Kape Technologies, who also own PIA, CyberGhost, and Intego (an antivirus software). Kape started by distributing malware for the Israeli government.