What works best free weights or machines?

There is a big debate about whether to use free weights or machines. In short, free weights involve more motor unit involvement. Motor units are are combination of nerves, muscle fibers and soft tissue that are connected physically to and activated electrically to the spine.

Machines don't usually require any balancing such as when doing a free weight bench press.

Machines tend to be safer because if you let go, there is probably nothing that will drop on you and injury you like a barbell will (if, for instance, a barbell slips when doing a bench press).

good luck to you in whatever you choose, one or the other or both.