PPTP is incredibly insecure as you've stated and provides next to no security whatsoever, there are tons of vulnerabilities in it and should be avoided at all costs. You can read more about those vulnerabilities here if you scroll down to Security
L2TP should always obviously be used with
L2TP doesn't actually feature any encryption if you run it as a standalone, which is why you will mostly see it paired with
IPSec tends to be pretty secure. Below is a list of the Cryptographic algorithms used in
- Authenticity & Integrity Protection
3DES-CBC it can also use
AES-GCM it's worth noting that
AES-GCM will also do authentication, so that could be a reason for choosing it.
Forgot to add that
IPSec will also perform a
Diffie Hellman exchange before data is ever sent across a link.
You can refer to RFC7321 to learn more about
IPSec here is a very, exceptional article on Cisco forums on how
IPSec actually works, I'd highly recommend reading it as it goes into a lot more detail than my post.