Is it harder to become a brain or heart surgeon?

It's what you like: I am not a brain surgeon but i can tell you that both take a great deal of sucrifice and commitment. So it really comes down to what you like to do the most.

Neither: Neither, it is different but both specialties require similar dedication.

Cardiac is hardest: While neurosurgeons might protest, the training for cardiac surgery is much longer. It requires board certification in both general and thoracic surgery and is far more intense. The vast majority of neurosurgeons rarely touch a brain. They are overwhelmingly involved with back or spine (bone) surgery, most of which is outpatient or minor surgery. There is no such thing as minor heart surgery.

BRAIN!!!: The brain surgeons will say their subspecialty is more difficult, the heart surgeons will say theirs is. Neurosurgery is the longest residency you can match into directly out of medical school. In my opinion, once you can replace the organ(heart transplant), you've progressed about as far as possible. Cardiac surgery is more advanced than neurosurgery because the heart is easier to understand.

Hard to say: I suppose it depends on who you ask. Both are very difficult.