I have a VPN service which gives me the option of connecting via PPTP, IPsec, or L2TP over IPsec. PPTP i know is inferior in terms of security and encryption, but I'm not really sure what the difference is between the two IPsec options.
Anecdotally, I've noticed that L2TP over IPsec seems to be much slower than plain IPsec, but that could be simply the servers, their configurations, or even the device on my end.
Is there any difference security-wise? Is one "better" than the other, or are they just functionally equivalent but differently implemented?