A very general outline on how to select a good VPN provider.

Paid or Free?
- Paid
There is no free lunch in this world.

Why it is not recommended to use free VPN is because it may be programmed to steal and/or key-logged your information and sell/provide to regulators/3rd parties. In some cases. it could infect your device(s) turn it into botnet.

A recent article: https://restoreprivacy.com/six-vpn-apps-introduced-botnet-malware-on-systems-since-2014/

Logging of activity?
- Make sure it had "No logging" policy backed up infrastructure report audited by independent 3rd parties.

Do you want the authorities/regulators come after you even though you are using VPN to mask your activities?

Having a paid VPN provider with "No-Logging" policy ensure even they raid your VPN provider's office, they won't able to get anything out of it.

2 news link example from 1 paid vpn provider which explains that:
https://mullvad.net/en/blog/mullvad-vpn-was-subject-to-a-search-warrant-customer-data-not-compromised

https://mullvad.net/en/blog/update-the-swedish-authorities-answered-our-protocol-request

Offers anonymous payment?
- Yes, ensure it offers. Example of anonymous payment: Cryptocurrency, Gift cards, Apple Pay, Cash & etc.

This next probably authorities/regulators will go after on tracing of payment history.

There are also other factors to consider when selecting a good paid VPN provider:

- Does it offers Leak protection?
- What protocols it offers like example: Wireguard or OpenVPN?
- Does it support multihopping?
- What type of Encryption it offer like example: AES-256, RSA-4096, SHA-512?
- Where it is based on and does it has good privacy laws? If it is based in USA, I probably will think twice.  If it is based in Sweden or Switzerland high chance I will consider.

Article link to above explaining above: https://en.wikipedia.org/wiki/VPN_service

Another 2 good article link which is trusted and how it arrived at the choices and explain VPN what it can do and it's limitation below:

https://www.nytimes.com/wirecutter/reviews/best-vpn-service/

https://www.nytimes.com/wirecutter/guides/what-is-a-vpn

If there is any wrong assumptions made above, feel free to correct me as I am learning on the go.

Disclaimer
There is no perfect paid VPN provider that checks all boxes and if the government really wants to go after you, there is nothing to stop them from doing that.

I am using Mullvad VPN after reading, researching above information as it checks almost all the boxes, has almost all the preventive actions and is based in Sweden where it has good privacy laws.

The 2 main critical factors I based on is "No-Logging" policy and anonymous payment options as it almost 99.9999% leaves no traces behind.

Your choices may/might differs from mine depending on your needs/requirement.