1. OpenVPN is the choice for all power users of Windows, Mac OS X, Linux, iOS 5+ and Android 4+. If you need a fast and secure VPN, OpenVPN is the best choice and its auto reconnect also gives it unsurpassed stability.
  2. L2TP/IPSec is the choice for your mobile device. Both iOS (iPhone, iPad) and Android have native support for it aswell as Windows and Mac OS X, so you don’t have to install anything. It is also more secure and stable then PPTP.
  3. PPTP is an old technology with low security that should only be used when nothing else is available or on old devices that only support PPTP. All versions of Windows, Mac OS X, Linux and most mobile systems have built in support for PPTP.