"Which is the best...........?"
WEP is the original WiFi security protocol and it's encryption is so weak that it can be hacked in minutes so it should never be used nowadays.
The third one offers very strong security but it requires a separate authentication server so it's only useful for business networks.
The one you're using out of the three is the best one for a home user as it provides strong protection. However, for maximum security, the newer WPA2 should be used if that option is available.