What is recommended if i wanted to allow users to register

What is recommended if i wanted to allow users to register or login from their Social accounts (facebook, Twitter, Google+) etc. I am concerned for safety but want convenience and ease for users.

Any recommendations as to what could be used to accomplish this ? If you guys offered such a plugin i would not hesitate but i did not see any thing like that available here. Please share any known ways to accomplish the social login.