For quad growth
For quad growth, safety bar squat and Smith machine squat score the same on every criterion, so use whichever is free, or both.
Both are good choices that train the quads the same way, so they swap freely. Rotating between them every few weeks is an easy way to vary your training.
The research score comes from these, scored by hand from the studies. Lifter scores appear once an exercise has 10 ratings. How scores work
Safety Bar Squat. A more upright squat than a back squat, which suits the quads and spares the shoulders.
Smith Machine Squat. A squat on rails, so you can place your feet forward and push the quads hard without balancing a bar.
For quad growth, safety bar squat and Smith machine squat score the same on every criterion, so use whichever is free, or both. Both are good choices that train the quads the same way, so they swap freely. Rotating between them every few weeks is an easy way to vary your training.
Smith machine squat is easier: it’s easy to learn, while safety bar squat takes some practice.
Safety bar squat needs a barbell and a squat rack, so for most people it’s a gym exercise. Smith machine squat needs a Smith machine, so for most people it’s a gym exercise.
About the same: both rate Strong for joint and recovery cost in our research rubric.