They are both good.
Machines will help you with perfect form and also speed up your workout because it takes less time to move a pin on a plate than it does to take off a collar ring and weights from a bar.
Free weights are more flexible as to variety of exercises one can do and do take more concentration.
-------------- "A will finds a way, failure is not an option"
Ivan
carivan@freetrainers.com
Montreal Canada