The number 1 rated Free VPN is Hotspot Shield and it is the best free VPN in my opinion as well.
I've used other free VPN services and nothing has come close to being as great as the Hotspot Shield VPN so I would recommend you try them.
Some other good free VPN services though are PrivateTunnel, SurfEasy, Hide.me, Speedify, ProtonVPN, Windscribe and Tunnelbear.
There are several other free VPN services out there but those are the best free ones although I would highly recommend using Hotspot Shield VPN as it's what I love the best.
But you may like a different one and sometimes paying for a good VPN service can be worth it but those free VPN services are good.