If you are looking for a site to site vpn,
pfSense, smoothwall, Untangle, etc. would be a good choice. You don't need to mess with the details of the vpn connection by just using the gui.
A good cross platform client to site vpn is
openvpn. This type of VPN works good through NAT and is easily setup through a firewall. There are clients for windows, linux, iOS, and I assume android since it is linux based.