How should a freelancer determine their fee per hour?

[Btaliat]

To be honest, these days most freelancers don't charge based on hour again. They prefer charging based on the outcomes of the tasks. They believe that doing that will make them get more money than charging per hour. For instance, charging per hour seems the freelancers are only limiting themselves. It is always better when they charge based on the tasks as whole. What do you think about this? Do you charge them based on hour or based on the outcome?