For both training purposes and muscle development, you want freeweights such as kettlebells, dumbbells, and barbells. Machines are worse than useless. They isolate muscles, which results in differential muscle development. This tends to result in an underdeveloped core as compared to your larger muscles. This can be risky for anybody, but it is especially risky for a berserker, because the gangr amplifies your natural strength by stimulating greater than usual muscle contraction. With underdeveloped core and stabilizer muscles, this can easily result in serious injuries, as you lift something that is technically in your strength range but which you are not able to adequately support when it moves freely.