It’s the age old argument and bodybuilders will forever disagree as to whether free-weights or machines are better.
When I was training for the Mr Universe, obviously I was doing a lot of free-weight exercises, whilst using some machines. Back in the day, I was also pushing some monster weights. However, as I’m now in my sixties, I tend to use mostly machines in my training now and this is for a number of reasons:

1. Machines take the need to balance weights out of the equation and this means that I am less likely to injure a wrist, elbow or other joint, during my training.
2. I can rep-out closer to failure on a machine, so for me, it’s a safer option. Remember that when I was training for the Mr Universe title, I always had a spotter working with me. I suppose the same could be said for a training partner – though I preferred to train on my own. If I was performing heavy bench presses, I would literally have to push less weight – which defeats the object.
3. Machines allow me to hit various muscles in a more isolated fashion and they are even designed to mimic the muscle-strength curve. Basically, machines are designed to be heavy and less heavy during completion of the movement.
4. Machines are faster and I’m not having to run around looking for plates etc. I might have retired from competitive bodybuilding, but I’m still competing even today – against the clock!

Ultimately, it’s down to the individual, but I would say that 90% of my post competition training is done with machines.