I’d have to agree with Shawn in my opinion I’d say all machines, they say machines are more safe and they’ll provide less impact and stress on the joints and I agree with that, but at the same time if you know how to use other piece of equipment properly such as the BOSU, TRX, med balls, etc. You shouldn’t have any problems. Plus machines make exercise/workouts boring because you can’t add that much veriety and you can’t change it up, you have to stick to pretty much one plane of movement.
Creativity is key. I don’t throw out the baby with the bath-water because some machines people hate or don’t think are safe for anyone frankly can be safe and effective IF DONE PROPERLY. Example…the leg extension machines with the foot too far behind the knees–dangerous…change the range of motion and it is not only safe for many but recommended by orthopedic surgeons and physical therapists. The Smith Machine…most I see on it use it improperly and even dangerously while others use it in an ineffective manner. Although I primarily stay away from machines of any kind, there are times when the machines can be handy and can add variety.