It was recommended that free weight bench press should be used for greater upper - body muscular development because it stimulates greater muscle activation. (getthisstrength.com)
Free weight benches as a category covers a range of muscle - targeting options. (fitnessultimate.com)
For example, middle (but not anterior) deltoid activation tends to be greater during free weight bench presses compared to Smith machine bench presses (Schick et al. 2010). (strengthandconditioningresearch.com)