Adjustable sandbag weights or fixed silicone bands — which is better?

It depends on use. Reviewers favor adjustable sandbag cuffs (like Sportneer and APEXUP) for progressive overload and strength work because you can add or remove load. Soft silicone bands (like Bala Bangles) score higher for comfort, low-bulk wear during Pilates, barre and walking, but offer less total resistance and fewer weight steps.