Depends on what you want to do??
If you want to build mass, there is nothing better than basic free weights - Bench, Squats, and Deadlifts. If you want to gain definifition after you have the size, machines work very well. Also most machines are designed to take pressure off joints, if you have injuries or aches. They will build mass also to some extent, but you don't use all your stabilizing muscles like you do with free weights.
I dont like machines, I only use free weights. I get better results from lifting the actual weight, not lifting through pulleys. That is just me though. I tried doing lat pull downs cause I cant hardly do my bodyweight, and saw zero growth, so I quit using it, and that is the only machine I use.
I use free weights when I work out with someone, a combinating of free weights and machines when I work out alone (which is 1/3 of the time).
I think mixing it up is a good idea. The fact that I can lift more weight on a machine than on a bench tells me that the machine is either doing more work than I think or those secondary muscles get off easy.
I'd have to agree with most here . Both will work . I do prefer free weights for a good solid pump as well as the balance aspect of it . But when you got no spot and you want to work to exaustion nothing like the saftey of the machines .