IKEv2 (Internet Key Exchange Protocol Version 2)
IKEv2 is considered to be a more secured extension of IPSec due it's ability to switch between Wifi and mobile networks without interruption.
L2TP (Layer 2 Tunneling Protocol)
L2TP is best for mobile devices that are not compatible with the OpenVPN protocol.
PPTP (Point-to-Point Tunneling Protocol)
PPTP is a last resort usage with it's older operating system due many security vulnerabilities and is considered useful when other systems aren't working
Use this protocol whenever possible. Allows for multiple types of authentication methods, but ultimately uses SSL/TLS (similar to your web browser) for key exchange. While it typically offers faster access speeds than L2TP, it also requires a third-party software and certificate files to be installed in order to use it — unless, of course, you’re using the IPVanish software. Also, support for mobile devices is limited. TCP (Transmission Control Protocol) OpenVPN over TCP is the most popular and reliable VPN connection type. It uses error correction to prevent the loss of information packets during data transfer. These lost packets would ultimately lead to failed websites and incomplete downloads if not for TCP’s automatic retransmitting of them. UDP (User Datagram Protocol) OpenVPN over UDP is often faster than TCP due to having no error correction. While lost packets are inevitable using UDP, certain web technologies are better experienced this way, particularly VoIP and online gaming, where real-time interaction would be interrupted by old, retransmitted data.
IPSec (Internet Protocol Security)
IPSec is a protocol suite that encrypts IP packets for transport and tunneling. Available for most mobile devices, IPsec protects all application traffic over an IP network. But unlike OpenVPN, PPTP and other connection types, IPSec does not define a particular encryption algorithm or an authentication function in and of itself -- it simply provides a framework for secure transport.