What do you trust more and are implementing today - Multi-factor authentication or single-sign on ?

SSO is a security concern if it is used in third party websites. There has been a recent spate of breached including Flipboard where social media SSO application tokens eg Google, used for authentication were leaked.

I trust MFA 

SSO as long as there are multiple options.
MFA as long as it is real MFA, SMS is not MFA,

I do both not only from security perspective, but also for the ease of access for users (SSO).