HSS is free but that version isn't really a VPN, it's more of a proxy. Its paid version i guess is a proper VPN. I've only used its free ver but have heard the paid one's decent. Same is the case with Cyberghost. You should also check out the difference between paid and free VPNs and Proxy vs VPN before you pick any VPN whatsoever. Just a friendly suggestion.
My personal experience with Ivacy VPN has been great so far. SO you should give that a try too.
As an insurance policy. if you are inclined towards an option, go for the paid one. You can always get one with a trial or a refund policy to assess the service. For anonymity, there are certain things you need to ask yourself before you pick a VPN, like:
- What do you need a VPN for? (activities)
- What's your definition of anonymity?
- What counts as an anonymous VPN for you?
- What's the region you live in?
- Where's the VPN you're buying, registered?
Again, read more on anonymous VPN before you proceed as well.
Honestly, not sure about the brand most secure vpn.