It all depends on what machines we're talking about.... Wee-hours-of-the-morning infomercial machines are worth their weight in recyclable tin and plastic, but real machines used correctly are a key part of my workout, as I bet they are with a lot of seasoned lifters. For me, it's free weights 70% and machines 30%... I've been lifting for 25+ years. My fundamentals are my free weights (smith machine since I work out alone), and my preacher bench, and my dumbells. However, I'd hate to be without a pec deck, and my high pulley. I have back trouble, so I have to be careful with shoulder presses, dead lifts, or military presses. I use the smith machine (a real Parabody professional one; not a Sears cheapie), for benching and and shoulder/military presses. I use the pec deck in addition to dumbell flys, and it works well for me. And the high pulley is way better for me, than trying to strap plates on my waist and doing pullups (low ceiling; would hit head on fans)... I can pull down whatever I want, with my legs clamped in place. I also use it for rows, in addition to bentover dumbell rows. For legs, I go pretty much all machine since I have bad knees. My leg gym consists of a lying leg curl, seated extension, and seated press (all selectorized type). I do have a plate-loaded hack squat machine, but I can't honestly say it's part of my regular routine.
Charles