I like using the hammer strength machines because I can load up a bunch of weight without a spotter and go to fatigue. It also feels more comfortable to me, probably since I am not having to balance the weight. I have always heard that free weights are better, but when I was watching Hard Knocks on HBO it appeared they were mainly using hammer strength machines and I believe they also use them a lot in college football. My guess is a combination of the 2 is best, but just wanted to see what others were doing.