As you probably have already noticed, the number of VPN providers has grown
massively in the recent years, and you can now stumble on ads for VPN
subscriptions on every corner of the Internet. Of course, not all of these
providers are equal in terms of quality of service, security or privacy. At the
contrary, some of them falsely claim to have a zero-log policy or to even
protect you from malicious actors.
Having said that, using a public VPN service is not necessarily a bad idea if
you choose it correctly. It's a matter of trust after all. Who do you trust the
most for keeping your traffic private, your ISP, or a carefully selected VPN
provider? (I said carefully here because you have a larger number of VPN
providers on the market than ISPs available where you live).
If you trust your VPN provider, you get in theory a higher degree of online
privacy by proxying your connections through it (even if, as of today, nothing
can fully replace Tor). But what about security? From a theoretical
standpoint once again, TLS is well enough to guarantee the security of your
online activity. And thanks to projects like Let's Encrypt, most
websites are accessible via HTTPS these days.