PPTP – this is an old VPN technology that uses very weak encryption algorithm of 128-bit. Decrypt PPTP traffic is not difficult. However, PPTP has a high data rate and the most common, with support for virtually any operating system. If you are willing to close their eyes to the safety and anonymity (for example, Torrent, online games, etc.), and the main thing for you is the speed of PPTP – your choice.
L2TP – this is a more modern VPN protocol, which came to replace PPTP, L2TP uses 128-bit encryption, but a crypto-stable unlike PPTP. L2TP is slightly lower prevalence of and support for the OS than PPTP. The data transfer rate of less than about 15-20% of PPTP.
OpenVPN – is the most kriptoustoychivy encryption method (256-bit encryption, used a 2048-bit key), each customer has its own unique certificate to connect. Traffic transmitted OpenVPN can not be decrypted without the private certificate. The data transfer speed is not much inferior to L2TP, but the prevalence is practically no OS (configure OpenVPN can only install special VPN client).
OpenVPN TCP – the main difference from the usual OpenVPN is the use of the TCP protocol and connect to port 443, the protocol used for data transmission WEB sites using SSL certificate. If your ISP blocks OpenVPN, it is possible to OpenVPN TCP will work. As this type of connection is useful for those users who want to hide the fact of using the VPN, because ISP and other supervisory authorities in the monitoring of your traffic will assume that you simply are communicating with one of HTTPS sites.