Everything has its place.

Barbells and dumbbells (AKA Free Weights) are the best choices to improve your balance and overall stability. Exercises will be harder to perform, because you will need to activate your core as you perform the movements. 

Machines should not be left out, however, especially for BODYBUILDING. They allow you to isolate certain muscles very easily, and because your balance and stability are not required as much, you can usually lift heavier weights. 

Try your best to include all three types of weights in your training regime.

Related Questions:

1. What is the best split for muscle gain? Can I gain muscle doing full body splits?