Hey,
Best and Free when it comes to VPNs are often two separate circles in a Venn Diagram that never touch. As many other answers in this question allude to, youre often compromising something when it comes to a free VPN service. A recent discussion around the topic involved a Free VPN Network exploiting its users IP and allowing others to do damaging things. Its essentially like handing over your digital thumbprint for anyone to use however they wanted to.
Regards
Gementciex