Using a Smiths machine for anything apart from injury rehab is a big no. Major reduction in planes of movement with a smithy and especially with squatting they do get you to use bad technique. The bench press is nothing but an ego exercise. You need to mix things up, include DB presses and loaded press ups (raised legs, depth presses) as you are currently not challening you neuromuscular system as it is just used to the same old movement

Free barbell = more planes of movement = greater control requirement = greater need for more muscle fibre recruitment