Not all VPN services are equally good. With free VPNs, you can save a ton of money, but only at the expense of your own security.
Other VPN services may have the most advanced security system and terribly low connection speeds (the more complex the encryption, the lower the speed - this is an axiom). Of course, such a service is not very suitable for those who just want to watch streams and streaming videos.
Choosing a VPN service, you should consider just a lot of factors. Speed is important for some, safety is for some.