My heart. If only my head was as stubborn as my heart I would probably be so much more successful in every aspect of my life.
Sadly though, the heart wins when the heart wants something.
Mind you, I can't really say my heart has always brought me bad luck. Many times, my heart knows what's right and wrong and it's brought me fortune my head probably wouldn't have thought of.
But I do wish I could use my head more than my heart. My heart is an extremist and gets me in a lot of trouble most of the time. Whereas my head is the mutual communicator. It knows what's right and wrong putting all emotions aside. It doesn't push for the illusion of the right but for the reality of it.