Which is more important -- a good process or a good outcome?

In the long run, a good process will be more likely to result in better outcomes over time.
Let's say you want to hire a new employee.  You can get lucky once or twice with a poor selection and hiring process, but over time your luck will start to fail you.

The problem with good luck and bad processes is that it can be hard to tell them apart.  Thus, an incompetent person who does not know what he is doing can be labeled a genius because of some short term good luck.  And once labeled a genius, it can be hard to recognize or admit a person's incompetence until major damage has occurred.

Therefore, it is essential to employ good processes in order to achieve good outcomes.