There is no such thing as the most secure password, and even if there were, posting it here would render it insecure because thousands of other people would use it on their accounts. Secure passwords, on the other hand, are made up of at least 16 to 20 characters and appear to be a random combination of numbers, letters, and symbols.
Short passwords are less secure than long passwords. We recommend passwords of 16 to 20 characters in length, yet more than half of all Americans use passwords of eight characters or fewer.