rule of thumb is if you want to gain muscle mass and size and weight use free weights. If you want to tone and increase flexibility use machines and pulleys. The best exercise routine is a mix of both. You can control the weight w/ machines and cables thus giving you more of a stretch plus they are nice if you don't have a spotter.
The main thing is to always keep switching it up. Do not stick w/ one routine w/ the same exercises and same machines. Your body/muscles is a memory bank and will remember these movements and will stop growing. You need to constantly shock your body so it cannot get used to an exercise regimen. Using a combination of machines, pulleys and free weights will hit the muscle in every possible way giving you the best pump(pump-caused by tearing of the muscle and large volume of blood being pumped to that muscle). If you feel you are no longer getting a pump you need to change something up i.e. grip, amount of weight, exercise, etc.
I may have went a little overboard w/ the details. I guess I get excited when I start talking about weight lifting, body building, nutritional supplementation, etc. I'm heavily into it (lift at least 5 days a week) and have a pretty large knowledge base on the subject. Any questions feel free to ask
