Buyers should prioritize motor type and power, specifically looking for brushless DC motors which offer higher torque, quieter operation, and a longer lifespan. For percussion massagers, the amplitude (stroke length) should be between 10mm to 16mm for deep tissue penetration. Additionally, ensure the battery capacity is at least 2500mAh to guarantee a continuous runtime of 3-5 hours, and verify that the stall force meets the requirements of your target market (typically 30-60 lbs for professional use).